func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 100;   int n, x, t;   long long ans, s[N];   int main() {     scanf( %d , &n);     for (int i = 1; i <= n; ++i) {       scanf( %d , &x);       t = 0;       while (x) {         t += x % 2;         x /= 2;       }       ++s[t];     }     for (int i = 1; i <= N; ++i) ans += s[i] * (s[i] - 1) / 2;     cout << ans;   }   