func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 505, mod = 1e9 + 7;   int n, m, e[N][N], f[N][N], g[N][N];   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     cin >> n;     for (int i = (1); i <= (n); i++)       for (int j = (1); j <= (n); j++) cin >> e[i][j];     for (int i = (1); i <= (n); i++) g[i][i] = f[i][i] = 1;     for (int len = (1); len <= (n); len++)       for (int l = (1); l <= (n - len + 1); l++) {         int r = l + len - 1;         for (int k = (l); k <= (r - 1); k++)           if (e[l][r]) (g[l][r] += (long long)f[l][k] * f[k + 1][r] % mod) %= mod;         for (int k = (l + 1); k <= (r); k++)           (f[l][r] += (long long)g[l][k] * f[k][r] % mod) %= mod;       }     cout << f[1][n] <<   n ;     return 0;   }   