func_code_string: #include <bits/stdc++.h>   using namespace std;   struct node {     int x, id;   } s[100101];   bool cmp(node a, node b) { return a.x < b.x; }   int main() {     int n, i, j, x;     cin >> n;     for (i = 0; i < n; i++) {       cin >> s[i].x;       s[i].id = i + 1;     }     sort(s, s + n, cmp);     if (n % 2)       x = n / 2 + 1;     else       x = n / 2;     cout << x << endl;     for (i = 0; i < n; i += 2) cout << s[i].id <<    ;     cout << endl << n - x << endl;     for (i = 1; i < n; i += 2) cout << s[i].id <<    ;     cout << endl;   }   