func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     int a[n];     for (int i = 1; i <= n; i++) cin >> a[i];     for (int i = 1; i <= n; i++) {       int temp1, temp2;       if (a[i] != i) {         temp1 = a[a[i]];         temp2 = a[a[a[i]]];         if (i == temp2) {           cout <<  yes  << endl;           break;         }         if (i == n && (temp2 != i)) {           cout <<  no  << endl;           break;         }       }     }   }   