#include <bits/stdc++.h>   using namespace std;   const int N = 2e5 + 10;   int n, a[N];   int main() {     cin >> n;     for (int i = 1; i <= n; i++) cin >> a[i];     int s = 0;     for (int i = 1; i <= n; i++) s ^= a[i];     if (n % 2 == 0) {       if (s != 0) {         cout <<  NO n ;         return 0;       }       n--;     }     cout <<  YES n ;     cout << n - 2 <<   n ;     for (int i = 1; i <= n - 2; i += 2)       cout << i <<     << i + 1 <<     << i + 2 <<   n ;     for (int i = 1; i <= n - 4; i += 2)       cout << i <<     << i + 1 <<     << n <<   n ;     return 0;   }   