func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, m;     cin >> n >> m;     vector<long long> p(n + 1, 1);     for (int i = 1; i <= n; ++i) p[i] = p[i - 1] * 7;     vector<long long> h(n + 1, 0);     for (int i = 0; i < m; ++i) {       int x, y;       cin >> x >> y;       h[x] += p[y];       h[y] += p[x];     }     vector<long long> hh(n + 1, 0);     for (int i = 0; i <= n; ++i) {       hh[i] = h[i] + p[i];     }     sort(h.begin() + 1, h.end());     sort(hh.begin() + 1, hh.end());     long long res = 0;     for (int i = 1, cnt = 0; i <= n; ++i) {       if (h[i] == h[i - 1])         res += cnt++;       else         cnt = 1;     }     for (int i = 1, cnt = 0; i <= n; ++i) {       if (hh[i] == hh[i - 1])         res += cnt++;       else         cnt = 1;     }     cout << res << endl;     return 0;   }   