func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m, x;   long long f[1510], g[1510];   long long sum[1510];   int main() {     memset(f, 0, sizeof(f));     scanf( %d%d , &n, &m);     for (int i = 0; i < n; ++i) {       scanf( %d , &x);       sum[0] = x;       for (int j = 1; j < m; ++j) {         scanf( %d , &x);         sum[j] = sum[j - 1] + x;       }       if (i == 0) {         for (int j = 0; j < m; ++j) f[j] = sum[j];       } else if ((i & 1) == 1) {         long long cm = f[m - 1];         for (int j = m - 2; j >= 0; --j) {           g[j] = sum[j] + cm;           cm = max(cm, f[j]);         }         for (int j = 0; j < m - 1; ++j) f[j] = g[j];       } else {         long long cm = f[0];         for (int j = 1; j < m; ++j) {           g[j] = sum[j] + cm;           cm = max(cm, f[j]);         }         for (int j = 1; j < m; ++j) f[j] = g[j];       }     }     long long ans = -9999999999999999ll;     if ((n & 1) == 0) {       for (int i = 0; i < m - 1; ++i) ans = max(f[i], ans);     } else {       for (int i = 1; i < m; ++i) ans = max(f[i], ans);     }     cout << ans << endl;     return 0;   }   