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#include "palindromy.h"
#include "message.h"
#include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for(int _n=n, i=0;i<_n;++i)
#define FOR(i,a,b) for(int i=(a),_b=(b);i<=_b;++i)
#define FORD(i,a,b) for(int i=(a),_b=(b);i>=_b;--i)
#define TRACE(x) cerr << "TRACE(" #x ")" << endl;
#define DEBUG(x) cerr << #x << " = " << (x) << endl;

typedef long long LL;
const int INF = 1000000000; const LL INFLL = LL(INF) * LL(INF);
template<class T> inline int size(const T&x) { return x.size(); }

LL NODE;
LL NNODES;

template<class T>
void Put(int node, const T&x) {
  static_assert(is_pod<T>(), "Put pod");
  const char *p = reinterpret_cast<const char*>(&x);
  for(size_t i=0;i<sizeof(T);++i) PutChar(node, p[i]);
}

template<class T>
void Put(int node, const vector<T> &x) {
  PutLL(node, x.size());
  for(const T&a : x) Put(node, a);
}

template<class T>
void SendTo(int node, const T&x) {
  Put(node, x);
  Send(node);
}

template<class T>
void Get(int node, T &x) {
  static_assert(is_pod<T>(), "Get pod");
  char *p = reinterpret_cast<char*>(&x);
  for(size_t i=0;i<sizeof(T);++i) p[i] = GetChar(node);
}

template<class T>
void Get(int node, vector<T> &x) {
  x.resize(GetLL(node));
  for(T &a : x) Get(node, a);
}

template<class T>
int ReceiveFrom(int node, T &x) {
  node = Receive(node);
  Get(node, x);
  return node;
}

/////////

template<class T>
class Array {
 public:
  explicit Array() : a(0), b(0), v() {}
  explicit Array(long long _a, long long _b) : a(_a), b(_b), v(_b - _a) {}
  void resize(long long _a, long long _b) {
    a = _a;
    b = _b;
    v.assign(_b - _a, T());
  }
  void assign(long long _a, long long _b, const T &x) {
    a = _a;
    b = _b;
    v.assign(_b - _a, x);
  }
  T &operator[](long long x) { return v[x-a]; }
  const T &operator[](long long x) const { return v[x-a]; }
  long long beginIdx() const { return a; }
  long long endIdx() const { return b; }
  typename vector<T>::const_iterator begin() const { return v.begin(); }
  typename vector<T>::iterator begin() { return v.begin(); }
  typename vector<T>::const_iterator end() const { return v.end(); }
  typename vector<T>::iterator end() { return v.end(); }
 private:
  long long a, b;
  vector<T> v;
};

constexpr int MODULUS = std::numeric_limits<int>::max();

int ModPower(int a, LL b) {
  b %= MODULUS-1;
  if(b<0) b += (MODULUS-1);

  int res = 1;
  while(b) {
    if(b&1) res = (LL(res)*a)%MODULUS;
    b >>= 1;
    a = (LL(a)*a)%MODULUS;
  }
  return res;
}

const int NUM_BASES = 3;
const int BASES[NUM_BASES] = {
  1051994564,
  404438832,
  870807049};

struct Hash {
  int val[NUM_BASES];
  LL len;

  Hash() : val(), len(0) {}

  void appendChar(char c) {
    REP(i,NUM_BASES) {
      val[i] = (LL(val[i]) * BASES[i] + LL(c)) % MODULUS;
    }
    ++len;
  }

  void appendHash(const Hash &h);

  void SubtractPrefix(const Hash &h);
};

void Hash::appendHash(const Hash &h) {
  REP(i,NUM_BASES) {
    val[i] = (LL(val[i]) * ModPower(BASES[i], h.len) + h.val[i]) % MODULUS;
  }
  len += h.len;
}

void Hash::SubtractPrefix(const Hash &h) {
  len -= h.len;
  REP(i,NUM_BASES) {
    val[i] = ((LL(val[i]) - LL(h.val[i]) * ModPower(BASES[i], len)) % MODULUS + MODULUS) % MODULUS;
  }
}

inline bool operator==(const Hash &a, const Hash &b) {
  if(a.len != b.len) return false;
  REP(i,NUM_BASES) if(a.val[i] != b.val[i]) return false;
  return true;
}

constexpr LL BLOCK = 30000;
static_assert(BLOCK%2==0, "even block");

constexpr LL MASTER = 0;

LL N;
LL numBlocks;

LL myAlphaBlock;
LL myBetaBlock;
LL myAlpha;
LL myBeta;

LL longPalin;
Array<char> data;

Array<int> palinRadius;

vector<Hash> prefixHashes;
vector<Hash> revSuffixHashes;

char ReadChar(LL x) {
  if (x < 0) return '^';
  if (x >= N) return '$';
  return GetLetter(x/2);
}

void Initialize() {
  NNODES = NumberOfNodes();
  NODE = MyNodeId();
  N = 2 * GetLength();
  numBlocks = (N+BLOCK-1) / BLOCK;
  NNODES = min(NNODES, numBlocks);
  if (NODE>=NNODES) exit(0);

  myAlphaBlock = NODE * numBlocks / NNODES;
  myBetaBlock = (NODE+1) * numBlocks / NNODES;
  myAlpha = myAlphaBlock * BLOCK;
  myBeta = myBetaBlock * BLOCK;
}

void GetData() {
  longPalin = 2 * (myBeta - myAlpha);
  data.resize(myAlpha - longPalin, myBeta + longPalin);
  for (LL i = data.beginIdx(); i < data.endIdx(); i += 2) {
    data[i] = ReadChar(i);
    data[i+1] = data[i];
  }
}

Hash ComputeLocalForwardHash(LL alpha, LL beta) {
  Hash h;
  for (LL i=alpha;i<beta;++i) h.appendChar(data[i]);
  return h;
}

Hash ComputeLocalBackwardHash(LL alpha, LL beta) {
  Hash h;
  for (LL i=beta-1;i>=alpha;--i) h.appendChar(data[i]);
  return h;
}

void SendOutMyHashes() {
  vector<Hash> forwardHashes;
  vector<Hash> backwardHashes;
  LL myBlocks = myBetaBlock - myAlphaBlock;
  forwardHashes.reserve(myBlocks);
  backwardHashes.reserve(myBlocks);
  for (LL block = myAlphaBlock; block < myBetaBlock; ++block) {
    forwardHashes.push_back(ComputeLocalForwardHash(block * BLOCK, (block+1) * BLOCK));
    backwardHashes.push_back(ComputeLocalBackwardHash(block * BLOCK, (block+1) * BLOCK));
  }
  assert(size(forwardHashes) == myBlocks);
  assert(size(backwardHashes) == myBlocks);

  REP(node, NNODES) {
    Put(node, myBlocks);
    for (const auto &h : forwardHashes) {
      assert(h.len == BLOCK);
      REP(i, NUM_BASES) Put(node, h.val[i]);
    }
    for (const auto &h : backwardHashes) {
      assert(h.len == BLOCK);
      REP(i, NUM_BASES) Put(node, h.val[i]);
    }
    Send(node);
  }
}

void ReceiveHashes() {
  prefixHashes.reserve(numBlocks+1);
  revSuffixHashes.reserve(numBlocks+1);
  prefixHashes.push_back(Hash());
  REP(node, NNODES) {
    Receive(node);
    LL hisBlocks; Get(node, hisBlocks);
    for(LL i=0;i<hisBlocks;++i) {
      Hash h;
      h.len = BLOCK;
      REP(j, NUM_BASES) Get(node, h.val[j]);
      prefixHashes.push_back(h);
    }
    for(LL i=0;i<hisBlocks;++i) {
      Hash h;
      h.len = BLOCK;
      REP(j, NUM_BASES) Get(node, h.val[j]);
      revSuffixHashes.push_back(h);
    }
  }
  revSuffixHashes.push_back(Hash());
  assert(size(prefixHashes) == numBlocks+1);
  assert(size(revSuffixHashes) == numBlocks+1);

  for (LL i = 1; i <= numBlocks; ++i) {
    Hash h = prefixHashes[i-1];
    h.appendHash(prefixHashes[i]);
    prefixHashes[i] = h;
  }

  for (LL i = numBlocks-1; i>=0; --i) {
    Hash h = revSuffixHashes[i+1];
    h.appendHash(revSuffixHashes[i]);
    revSuffixHashes[i] = h;
  }
}

void ComputeShortPalin() {
  palinRadius.resize(myAlpha - longPalin, myBeta);
  LL currentLongStart = palinRadius.beginIdx();
  LL currentLongEnd = currentLongStart;

  for (LL x = myAlpha - longPalin; x < myBeta; ++x) {
    LL radius = 0;
    if (x < currentLongEnd) {
      radius = palinRadius[currentLongStart + currentLongEnd - x];
      if (x + radius > currentLongEnd) radius = currentLongEnd - x;
    }
    while (x-radius > myAlpha - longPalin && x+radius < myBeta + longPalin && data[x-radius-1] == data[x+radius]) ++radius;
    palinRadius[x] = radius;
    if(x+radius > currentLongEnd) {
      currentLongStart = x - radius;
      currentLongEnd = x + radius;
    }
  }
}

Hash ComputeBigPrefix(LL x) {
  LL b = x/BLOCK;
  Hash h = prefixHashes[b];
  for (LL i=b*BLOCK;i<x;++i) {
    h.appendChar(ReadChar(i));
  }
  return h;
}

Hash ComputeBigRevSuffix(LL x) {
  LL b = (x+BLOCK-1)/BLOCK;
  Hash h = revSuffixHashes[b];
  for (LL i = b*BLOCK-1; i>=x; --i) {
    h.appendChar(ReadChar(i));
  }
  return h;
}

Hash ComputeBigHash(LL alpha, LL beta) {
  Hash h = ComputeBigPrefix(beta);
  h.SubtractPrefix(ComputeBigPrefix(alpha));
  return h;
}

Hash ComputeBigRevHash(LL alpha, LL beta) {
  Hash h = ComputeBigRevSuffix(alpha);
  h.SubtractPrefix(ComputeBigRevSuffix(beta));
  return h;
}

bool RadiusOK(LL x, LL radius) {
  if(x-radius < 0 || x+radius > numBlocks*BLOCK) return false;
  return ComputeBigHash(x, x+radius) == ComputeBigRevHash(x-radius, x);
}

LL ComputeBigRadius(LL x) {
  LL alpha = 0;
  LL beta = 1;
  while(RadiusOK(x, beta)) { 
    alpha = beta;
    beta *= 2;
  }
  while(beta-alpha>1) {
    LL gamma = (alpha+beta)/2;
    if(RadiusOK(x, gamma)) alpha=gamma; else beta=gamma;
  }
  return alpha;
}

bool PeriodOK(const LL a, const LL b, const LL period) {
  assert(b-a >= period);
  if(a < 0 || b > numBlocks*BLOCK) return false;
  bool res= ComputeBigHash(a, b-period) == ComputeBigHash(a+period, b);
  return res;
}

void ExtendPeriodLeft(LL &a, const LL b, const LL period) {
  LL alpha = 0;
  LL beta = 1;
  while(PeriodOK(a-beta, b, period)) {
    alpha=beta;
    beta *= 2;
  }
  while(beta-alpha>1) {
    LL gamma = (alpha+beta)/2;
    if(PeriodOK(a-gamma, b, period)) alpha=gamma; else beta=gamma;
  }
  a -= alpha;
}

void ExtendPeriodRight(const LL a, LL &b, const LL period) {
  LL alpha = 0;
  LL beta = 1;
  while(PeriodOK(a, b+beta, period)) {
    alpha=beta;
    beta *= 2;
  }
  while(beta-alpha>1) {
    LL gamma = (alpha+beta)/2;
    if(PeriodOK(a, b+gamma, period)) alpha=gamma; else beta=gamma;
  }
  b += alpha;
}

void ComputeLongPalin() {
  LL numLong = 0;
  LL firstLong = 0;
  LL step = 0;
  LL lastLong = 0;

  for (LL x = myAlpha; x < myBeta; ++x) {
    if (palinRadius[x] < longPalin) continue;
    if (numLong==0) {
      firstLong = x;
    } else if (numLong==1) {
      step = x - firstLong;
      lastLong = x;
    } else {
      assert(step == x - lastLong);
      lastLong = x;
    }
    ++numLong;
  }

  if (numLong == 0) return;
  else if (numLong == 1) {
    palinRadius[firstLong] = ComputeBigRadius(firstLong);
  } else {
    LL period = 2 * step;
    LL periodStart = firstLong - longPalin;
    LL periodEnd = lastLong + longPalin;
    ExtendPeriodLeft(periodStart, periodEnd, period);
    ExtendPeriodRight(periodStart, periodEnd, period);
    for (LL x = firstLong; x <= lastLong; x += step) {
      if (x - periodStart < periodEnd - x) {
        palinRadius[x] = x-periodStart;
      } else if (x - periodStart > periodEnd - x) {
        palinRadius[x] = periodEnd-x;
      } else {
        palinRadius[x] = ComputeBigRadius(x);
      }
    }
  }
}

void SendAnswer() {
  LL answer = 0;
  for (LL x = myAlpha; x < myBeta && x < N; ++x) {
    // 0 -> 0
    // 1 -> 1    a|a
    // 2 -> 1    aa|aa
    // 3 -> 2    aab|baa
    answer += (palinRadius[x]+1)/2;
  }
  SendTo(MASTER, answer);
}

void CollectAnswers() {
  LL total = 0;
  REP(node, NNODES) {
    LL x; ReceiveFrom(node, x);
    total += x;
  }
  cout << total << '\n';
}

int main() {
  Initialize();
  GetData();
  SendOutMyHashes();
  ReceiveHashes();
  ComputeShortPalin();
  ComputeLongPalin();
  SendAnswer();
  if (NODE == MASTER) CollectAnswers();
}