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#include "message.h"
#include "maklib.h"
#include <iostream>
#include <cstdio>
#include <string>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <cmath>
#include <algorithm>
#include <sstream>
#include <stack>
#include <cstring>
#include <iomanip>
#include <ctime>
using namespace std;
#define pb push_back
#define INF 1001001001
#define FOR(i,n) for(int (i)=0;(i)<(n);++(i))
#define FORI(i,n) for(int (i)=1;(i)<=(n);++(i))
#define mp make_pair
#define pii pair<int,int>
#define ll long long
#define vi vector<int>
#define SZ(x) ((int)((x).size()))
#define fi first
#define se second
#define wez(n) int (n); scanf("%d",&(n));
#define wez2(n,m) int (n),(m); scanf("%d %d",&(n),&(m));
#define wez3(n,m,k) int (n),(m),(k); scanf("%d %d %d",&(n),&(m),&(k));
inline void pisz(int n) { printf("%d\n",n); }
template<typename T,typename TT> ostream& operator<<(ostream &s,pair<T,TT> t) {return s<<"("<<t.first<<","<<t.second<<")";}
template<typename T> ostream& operator<<(ostream &s,vector<T> t){FOR(i,SZ(t))s<<t[i]<<" ";return s; }
#define DBG(vari) cerr<<#vari<<" = "<<(vari)<<endl;
#define ALL(t) t.begin(),t.end()
#define FOREACH(i,t) for (typeof(t.begin()) i=t.begin(); i!=t.end(); i++)
#define TESTS wez(testow)while(testow--)
#define REP(i,a,b) for(int (i)=(a);(i)<=(b);++i)
#define REPD(i,a,b) for(int (i)=(a); (i)>=(b);--i)
#define REMAX(a,b) (a)=max((a),(b));
#define REMIN(a,b) (a)=min((a),(b));
#define IOS ios_base::sync_with_stdio(0);

int main () {
   int n = Size();
   int m = NumberOfNodes(), my = MyNodeId();
   if (n < m) {
      // brut
      if (my == 0) {
         ll best = 0, now = 0;
         REP(i,1,n) {
            now = max(0LL, now + ElementAt(i));
            best = max(best, now);
         }
         cout << best << endl;
      }
   } else {
      /*int bl = n / m; // bl >= 1
      int from = bl * my + 1, to = bl * (my + 1); // [from,to]
      if (my == m-1) to = n;*/
      int from = (1LL * n * my) / m + 1;
      int to = (1LL * n * (my + 1)) / m; // [from,to] 1-based
      
      ll best = 0, now = 0;
      ll sumFromStart = 0, bestFromStart = 0;
      REP(i,from,to) {
         int ti = ElementAt(i);
         now = max(0LL, now + ti);
         best = max(best, now);
         sumFromStart += ti;
         bestFromStart = max(bestFromStart, sumFromStart);
      }
      ll sumFromEnd = 0, bestFromEnd = 0;
      REPD(i,to,from) {
         int ti = ElementAt(i);
         sumFromEnd += ti;
         bestFromEnd = max(bestFromEnd, sumFromEnd);
      }
      PutLL(0, bestFromStart);
      PutLL(0, bestFromEnd);
      PutLL(0, best);
      PutLL(0, sumFromStart);
      //PutInt(0, from); PutInt(0, to);
      Send(0);
      
      if (my == 0) {
         best = 0;
         vector<ll> bFS, bFE, sum;
         //vi st, en;
         FOR(a,m) {
            Receive(a);
            bFS.pb(GetLL(a));
            bFE.pb(GetLL(a));
            best = max(best, GetLL(a));
            sum.pb(GetLL(a));
            //st.pb(GetInt(a)); en.pb(GetInt(a));
         }
         //DBG(bFS)DBG(bFE)DBG(sum)
         //DBG(st)DBG(en)
         FOR(a,m-1) REP(b,a+1,m-1) {
            ll cand = bFE[a] + bFS[b];
            REP(c,a+1,b-1) cand += sum[c];
            best = max(best, cand);
         }
         cout << best << endl;
      }
   }
   return 0;
}