#include <bits/stdc++.h>
using namespace std;
void preproc() {}
void solve() {
  long long n;
  cin >> n;
  vector<long long> a(n);
  bool equal = true;
  long long tot = 0;
  for (long long i = 0; i < n; ++i) {
    cin >> a[i];
    tot ^= a[i];
  }
  if ((n & 1) or (n % 2 == 0 and tot == 0)) {
    cout << "YES\n";
    n -= 1;
    cout << n / 2 + n / 2 << '\n';
    for (long long i = 0; i < n / 2; ++i) {
      cout << 1 << ' ' << 2 * i + 2 << ' ' << 2 * i + 3 << '\n';
    }
    for (long long i = 0; i < n / 2; ++i) {
      cout << 1 << ' ' << 2 * i + 2 << ' ' << 2 * i + 3 << '\n';
    }
  } else {
    cout << "NO\n";
  }
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.precision(10);
  cout << fixed;
  preproc();
  long long tc = 1;
  for (long long Tt = 1; Tt <= tc; ++Tt) {
    solve();
  }
  return EXIT_SUCCESS;
}
