func_code_string: #include <bits/stdc++.h>   int main() {     int n;     scanf( %d , &n);     int a[n];     for (int i = 0; i < n; ++i) {       scanf( %d , &a[i]);     }     int temp1, temp2, flag = 0;     for (int i = 0; i < n; ++i) {       temp1 = a[i] - 1;       temp2 = a[temp1] - 1;       if (a[temp2] - 1 == i) {         flag = 1;         printf( YES n );         break;       }     }     if (flag == 0) {       printf( NO n );     }     return 0;   }   