func_code_string: #include <bits/stdc++.h>   using namespace std;   long long gcd(long long a, long long b) {     while (a && b) a > b ? a %= b : b %= a;     return a + b;   }   long long lcm(long long a, long long b) { return a * b / gcd(a, b); }   int main() {     int n;     cin >> n;     int i, j, sum = 0, in;     int a[n];     for (i = 0; i < n; ++i) {       cin >> a[i];       sum += a[i];     }     int x = n / 2;     int avg = sum / x;     for (i = 0; i < n; i++) {       if (a[i] == 0) continue;       cout << i + 1 <<    ;       for (j = i + 1; j < n; j++) {         if (a[j] == 0) continue;         if ((a[j] + a[i]) == avg) {           cout << j + 1 <<    ;           a[j] = 0;           a[i] = 0;           break;         }       }       cout << endl;     }     return 0;   }   