#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
int num[N];
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> num[i];
  }
  if (n % 2) {
    cout << "YES" << endl << n - 1 << endl;
    for (int i = 2; i <= n; i += 2) {
      cout << "1 " << i << " " << i + 1 << endl;
    }
    for (int i = 2; i <= n; i += 2) {
      cout << "1 " << i << " " << i + 1 << endl;
    }
  } else {
    int xor_n = 0;
    for (int i = 1; i <= n; i++) xor_n ^= num[i];
    if (xor_n == 0) {
      cout << "YES" << endl << n - 2 << endl;
      for (int i = 2; i < n; i += 2) {
        cout << "1 " << i << " " << i + 1 << endl;
      }
      for (int i = 2; i < n; i += 2) {
        cout << "1 " << i << " " << i + 1 << endl;
      }
    } else {
      cout << "NO" << endl;
    }
  }
  return 0;
}
