func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class T>   inline void read(T& x) {     bool fu = 0;     char c;     for (c = getchar(); c <= 32; c = getchar())       ;     if (c ==  - ) fu = 1, c = getchar();     for (x = 0; c > 32; c = getchar()) x = x * 10 + c -  0 ;     if (fu) x = -x;   };   template <class T>   inline void read(T& x, T& y) {     read(x);     read(y);   }   template <class T>   inline void read(T& x, T& y, T& z) {     read(x);     read(y);     read(z);   }   inline char getc() {     char c;     for (c = getchar(); c <= 32; c = getchar())       ;     return c;   }   int n, m, st, i, j, k, l, K, P, x, y;   int D0[610], D1[610], n0[610], n1[610];   int e[610][610];   long long a[610][610];   bool vis[610];   long long f[610];   long long dfs(int i) {     if (i == st) return 1;     if (vis[i]) return f[i];     vis[i] = 1;     long long ans = 0;     for (int j = 1; j <= n; j++)       if (e[j][i]) ans = (ans + dfs(j) * e[j][i]) % P;     return f[i] = ans;   }   int main() {     read(n, m, P);     for (i = 1; i <= m; i++) read(x, y), e[x][y]++, D0[x]++, D1[y]++;     for (i = 1; i <= n; i++)       if (D0[i] == 0) n0[i] = ++n0[0];     for (i = 1; i <= n; i++)       if (D1[i] == 0) n1[i] = ++n1[0];     K = n0[0];     for (i = 1; i <= n; i++)       if (n1[i]) {         memset(vis, 0, sizeof(vis));         memset(f, 0, sizeof(f));         st = i;         for (j = 1; j <= n; j++)           if (n0[j]) a[n1[i]][n0[j]] = dfs(j);       }     long long ans = 1;     for (i = 1; i <= K; i++) {       for (j = i; j <= K; j++)         if (a[j][i]) {           if (j != i) ans = -ans;           for (k = i; k <= K; k++) swap(a[j][k], a[i][k]);           break;         }       if (a[i][i] == 0) continue;       for (j = i + 1; j <= K; j++)         while (a[j][i]) {           long long res = a[j][i] / a[i][i];           for (k = i; k <= K; k++) a[j][k] = (a[j][k] - a[i][k] * res) % P;           if (a[j][i]) {             ans = -ans;             for (k = i; k <= K; k++) swap(a[j][k], a[i][k]);           }         }     }     for (i = 1; i <= K; i++) ans = ans * a[i][i] % P;     if (ans < 0) ans += P;     cout << ans << endl;     return 0;   }   