func_code_string: #include <bits/stdc++.h>   using namespace std;   stringstream ss;   long long p[1000010], h1[1000010], h2[1000010];   int main() {     p[0] = 1;     for (int i = 1; i < 1000010; i++) h1[i] = p[i] = p[i - 1] * 127LL;     int n, m, a, b;     cin >> n >> m;     for (int i = 1; i <= m; i++) {       cin >> a >> b;       h1[a] += p[b];       h2[a] += p[b];       h1[b] += p[a];       h2[b] += p[a];     }     sort(h1 + 1, h1 + 1 + n);     sort(h2 + 1, h2 + 1 + n);     long long res = 0;     for (int i = 1; i <= n; i++) {       long long cnt = 1;       while (i + 1 <= n && h1[i] == h1[i + 1]) cnt++, i++;       res += (cnt) * (cnt - 1) / 2LL;     }     for (int i = 1; i <= n; i++) {       long long cnt = 1;       while (i + 1 <= n && h2[i] == h2[i + 1]) cnt++, i++;       res += (cnt) * (cnt - 1) / 2LL;     }     cout << res << endl;     return 0;   }   