func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     map<long long int, long long int> mpp;     long long int n;     cin >> n;     for (long long int i = 0; i < n; i++) {       long long int x;       cin >> x;       mpp[__builtin_popcount(x)]++;     }     long long int ans = 0;     for (auto p : mpp) {       ans += (p.second) * (p.second - 1) / 2;     }     cout << ans;   }   