#include <bits/stdc++.h>   const int MAXN = (int)1e5 + 5;   const int MODN = (int)1e9 + 7;   int inf = 0x3f3f3f3f;   using namespace std;   char str[MAXN];   int num[MAXN];   int a[MAXN];   int vis[MAXN];   int main() {     int n, m;     while (scanf( %d , &n) != EOF) {       memset(vis, 0, sizeof(vis));       int sum = 0;       for (int i = 0; i < n; i++) {         scanf( %d , &a[i]);         sum += a[i];       }       int it = sum * 2 / n;       for (int i = 0; i < n; i++) {         if (vis[i] == 0) {           vis[i] = 1;           printf( %d  , i + 1);           for (int j = 0; j < n; j++) {             if (vis[j] == 0 && a[j] + a[i] == it) {               vis[j] = 1;               printf( %d n , j + 1);               break;             }           }         }       }     }   }   