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#include <algorithm>
#include <cstdio>
#include <cstdlib>
#include <list>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <vector>
#include <cmath>
#include <cstring>
#include <string>
#include <iostream>
#include <complex>
#include <sstream>
#include <cassert>
using namespace std;

#include "message.h"
#include "palindromy.h"
 
typedef long long LL;
typedef unsigned long long ULL;
typedef long double LD;
typedef vector<int> VI;
typedef pair<int,int> PII;
 
#define REP(i,n) for(int i=0;i<(n);++i)
#define SIZE(c) ((int)((c).size()))
#define FOR(i,a,b) for (int i=(a); i<(b); ++i)
#define FOREACH(i,x) for (__typeof((x).begin()) i=(x).begin(); i!=(x).end(); ++i)
#define FORD(i,a,b) for (int i=(a)-1; i>=(b); --i)
#define ALL(v) (v).begin(), (v).end()
 
#define pb push_back
#define mp make_pair
#define st first
#define nd second

int NODES;
int ME;
int ORIGINAL_LENGTH;

// ...ABABABAB[oorriiggiinnaallABABABAB]ABABAB...
inline char get(int k) {
    if (k<0 || k >= 2 * ORIGINAL_LENGTH) return (k%2 ? 'A' : 'B');
    return GetLetter(k / 2);
}

struct Incomplete {
    int first;
    int second;
    int last;
    
    Incomplete(): first(-1), second(-1), last(-1) {}
};

void send(int target, const Incomplete& incomplete) {
    PutInt(target, incomplete.first);
    PutInt(target, incomplete.second);
    PutInt(target, incomplete.last);
    Send(target);
}

Incomplete receive(int source) {
    Incomplete incomplete;
    Receive(source);
    incomplete.first = GetInt(source);
    incomplete.second = GetInt(source);
    incomplete.last = GetInt(source);
    return incomplete;
}

Incomplete merge(const Incomplete& left, const Incomplete& right) {
    if (left.first == -1) return right;
    if (right.first == -1) return left;
    
    Incomplete result;
    result.first = left.first;
    result.last = right.last;
    result.second = (left.second != -1 ? left.second : right.first);
    return result;
}

int T[100000000];
int main() {
    NODES = NumberOfNodes();
    ME = MyNodeId();
    ORIGINAL_LENGTH = GetLength();
    
    int interval_length = (2 * ORIGINAL_LENGTH + NODES - 1) / NODES;
    
    int margin = 4 * interval_length;
    int start = ME * interval_length - margin;    
    int g = 0;
    FOR(i, 1, 5 * interval_length) {
        if (2*g-i >= 0) T[i] = max(min(T[2*g-i], T[g]+g-i), 0);
        while (T[i] < 4 * interval_length && i-T[i]-1 >= 0 && get(start+i+T[i]) == get(start+i-T[i]-1)) ++T[i];
        if (T[i]+i > T[g]+g) g=i;
    }
    
    LL result = 0;
    
    Incomplete incomplete;
    FOR(i,4*interval_length,5*interval_length) {
        if (T[i] >= 4*interval_length) {
            if (incomplete.first == -1) incomplete.first = i + start;
            else if (incomplete.second == -1) incomplete.second = i + start;
            incomplete.last = i + start;
        } else {
            result += (T[i]+1)/2;
            //printf("(1)[%d %d]\n", i+start, T[i]);
        }
    }
    
    int master = ME, nodes_per_interval = 1;
    while (interval_length < 2*ORIGINAL_LENGTH) {
        interval_length <<= 1;
        nodes_per_interval <<= 1;
        master -= master % nodes_per_interval;
        int previous_master = master + nodes_per_interval / 2;
        if (ME == previous_master) {
            send(master, incomplete);   
        }
        if (ME == master) {
            if (previous_master < NODES) {
                Incomplete second_part = receive(previous_master);
                incomplete = merge(incomplete, second_part);
            }
            FOR(i,1,nodes_per_interval) if (ME + i < NODES) send(ME+i, incomplete);
        } else {
            incomplete = receive(master);
        }

        if (incomplete.first == -1) continue;
        assert(master + nodes_per_interval <= NODES);
        
        bool need_to_check_single = true;
        int single_radius = 2*interval_length;
        if (incomplete.first < incomplete.last) {
            need_to_check_single = false;
        
            int interval_start = interval_length * (master / nodes_per_interval);
            int interval_end = interval_start + interval_length;
            int diff = (incomplete.second - incomplete.first);
            int cyc = 2 * diff;
            
            int L = incomplete.first - 2 * interval_length;
            L += (nodes_per_interval - L%nodes_per_interval) % nodes_per_interval;
            L += (ME - master);
            
            int R = incomplete.last + 2 * interval_length;
            R -= (R % nodes_per_interval);
            R += -nodes_per_interval + (ME - master);
            
            int startL = L, startR = R;
            do {
                L -= nodes_per_interval;
            } while (L >= interval_start - 4 * interval_length - 5 && get(L + cyc) == get(L));
            do {
                R += nodes_per_interval;
            } while (R <= interval_end + 4 * interval_length + 5 && get(R - cyc) == get(R));
            cyc = -1; // don't use
            
            if (ME != master) {
                PutInt(master, L);
                PutInt(master, R);
                Send(master);
            }        
            if (ME == master) {
                FOR(i,1,nodes_per_interval) {
                    Receive(ME+i);
                    L = max(L, GetInt(ME+i));
                    R = min(R, GetInt(ME+i));
                }
                FOR(i,1,nodes_per_interval) {
                    PutInt(ME+i, L);
                    PutInt(ME+i, R);
                    Send(ME+i);
                }
            }
            if (ME != master) {
                Receive(master);
                L = GetInt(master);
                R = GetInt(master);
            }
            
            int new_first = 1e9 + 500;
            int new_last = -1;
            for (int i = incomplete.first + (ME - master) * diff; i <= incomplete.last; i += nodes_per_interval * diff) {
                int radius = min(R - i, i-1 - L);
                if (radius >= 4 * interval_length || get(i - radius - 1) == get(i + radius)) {
                    new_first = min(new_first, i);
                    new_last = max(new_last, i);                
                    if (radius < 4 * interval_length) {
                        need_to_check_single = true;
                        single_radius = max(single_radius, radius);
                    }
                } else {
                    result += (radius+1)/2;
                }
            }

            if (ME != master) {
                PutInt(master, new_first);
                PutInt(master, new_last);
                PutInt(master, need_to_check_single);
                PutInt(master, single_radius);
                Send(master);
            }
            if (ME == master) {
                FOR(i,1,nodes_per_interval) {
                    Receive(ME + i);
                    new_first = min(new_first, GetInt(ME + i));
                    new_last = max(new_last, GetInt(ME + i));
                    need_to_check_single = GetInt(ME + i) || need_to_check_single;                
                    single_radius = max(single_radius, GetInt(ME+i));
                }
                FOR(i,1,nodes_per_interval) {
                    PutInt(ME+i, new_first);
                    PutInt(ME+i, new_last);
                    PutInt(ME+i, need_to_check_single);
                    PutInt(ME+i, single_radius);
                    Send(ME+i);
                }
            }
            if (ME != master) {
                Receive(master);
                new_first = GetInt(master);
                new_last = GetInt(master);
                need_to_check_single = GetInt(master) || need_to_check_single;                
                single_radius = max(single_radius, GetInt(master));
            }
            
            if (new_first > new_last) incomplete = Incomplete();
            else {
                incomplete.first = new_first;
                incomplete.last = new_last;
                incomplete.second = (incomplete.first == incomplete.last ? -1 : incomplete.first + diff);
            }
        }
        
        if (need_to_check_single && incomplete.first != -1 && incomplete.first == incomplete.last) {
            int c = incomplete.first;
            
            int radius = single_radius - (single_radius%nodes_per_interval) - nodes_per_interval + (ME - master);
            do {
                radius += nodes_per_interval;
            } while (radius <= 4 * interval_length + 5 && get(c + radius - 1) == get(c - radius));
            
            if (ME != master) {
                PutInt(master, radius);
                Send(master);
            } else {
                FOR(i,1,nodes_per_interval) {
                    Receive(ME + i);
                    radius = min(radius, GetInt(ME + i));
                }
            }
            --radius;
            if (ME == master) {
                if (radius < 4 * interval_length) {
                    //printf("(2)[%d %d]\n", c, radius);
                    result += (radius+1)/2;
                    incomplete.first = incomplete.second = incomplete.last = -1;
                }
            }
        }
    }
    
    if (ME > 0) {
        PutLL(0, result);
        Send(0);
    } else {
        //REP(i, LENGTH) printf("[%d]%c", i, get(i)); printf("\n");
        FOR(i,1,NODES) {
            Receive(i);
            result += GetLL(i);
        }
        printf("%lld\n", result);
    }
}