func_code_string: #include <bits/stdc++.h>   #pragma comment(linker,  /STACK:10000000000 )   #pragma GCC optimize( O3 )   using namespace std;   const int MOD = 1000000007;   const int INF = 1000000007LL;   const long long INF2 = 1000000007LL * 1000000007LL;   const long double EPS = 1e-9;   const int SIZE = 3010;   mt19937 rng(time(0));   uniform_int_distribution<int> uid(-1000000000, 1000000000);   struct fenwick {     int n;     vector<int> a;     fenwick() {}     fenwick(int n_) {       n = n_;       a.resize(n, 0);     }     int query(int r) {       if (r < 0) return 0;       int sum = 0;       for (int i = r; i >= 0; i = (i & (i + 1)) - 1) sum += a[i];       return sum;     }     int query(int l, int r) { return query(r) - query(l - 1); }     void increase(int ind, int val = 1) {       for (int i = ind; i < n; i = i | (i + 1)) a[i] += val;     }   };   int a[SIZE][SIZE], n, m;   int zl[SIZE][SIZE], zr[SIZE][SIZE], zld[SIZE][SIZE];   int get_num_diag(int i, int j) {     int num = i + j;     return num;   }   vector<vector<pair<int, int> > > endColumn;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     string s;     cin >> n >> m;     endColumn.resize(n + m + 10);     for (int i = 1; i <= n; ++i) {       cin >> s;       for (int j = 1; j <= m; ++j) {         a[i][j] = s[j - 1] ==  z ;         if (a[i][j]) zl[i][j] = a[i][j] + zl[i][j - 1];       }     }     for (int i = n; i >= 1; --i) {       for (int j = m; j >= 1; --j) {         if (a[i][j]) {           zr[i][j] = a[i][j] + zr[i][j + 1];           zld[i][j] = a[i][j] + zld[i + 1][j - 1];           endColumn[j + zr[i][j] - 1].push_back({i, j});         }       }     }     vector<fenwick> f(n + m + 10, fenwick(n + 10));     long long ans = 0;     for (int j = m; j >= 1; --j) {       for (auto& j : endColumn[j]) {         int i2 = j.first, j2 = j.second;         f[i2 + j2].increase(i2);       }       for (int i = 1; i <= n; ++i) {         if (!a[i][j]) continue;         int len = min(zl[i][j], zld[i][j]) - 1;         long long rs = f[i + j].query(i, i + len);         ans += rs;       }     }     cout << ans;     return 0;   }   