func_code_string: #include <bits/stdc++.h>   using namespace std;   int entries[1010000][2];   long long has[1010000];   long long power[1010000];   int main() {     int i, j;     long long ans = 0;     int n, m, u, v, p = 31;     scanf( %d%d , &n, &m);     power[0] = 1;     for (i = 1; i <= n; i++) power[i] = power[i - 1] * p;     for (i = 0; i < m; i++) {       scanf( %d%d , &u, &v);       u--;       v--;       has[u] += power[v];       has[v] += power[u];       entries[i][0] = u;       entries[i][1] = v;     }     for (i = 0; i < m; i++) {       u = entries[i][0];       v = entries[i][1];       if (has[u] + power[u] == has[v] + power[v]) ans++;     }     sort(has, has + n);     for (i = 0; i < n; i = j) {       for (j = i; j < n && has[j] == has[i]; j++)         ;       long long temp = j - i;       ans += temp * (temp - 1) / 2;     }     printf( %I64d n , ans);     return 0;   }   