#include <bits/stdc++.h>
#pragma comment(linker, "/stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimization("unroll-loops")
using namespace std;
template <typename Arg1>
void __f(const char* name, Arg1&& arg1) {
  cerr << name << " : " << arg1 << endl;
}
template <typename Arg1, typename... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cerr.write(names, comma - names) << " : " << arg1 << " | ";
  __f(comma + 1, args...);
}
const int N = 1e5 + 5;
int n, a[N];
void solve() {
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  int xr = 0;
  for (int i = 1; i <= n; i++) xr ^= a[i];
  if (n % 2) {
    vector<vector<int> > ans;
    for (int i = 2; i <= n; i += 2) {
      vector<int> v = {1, i, i + 1};
      ans.push_back(v);
    }
    for (int i = 2; i <= n - 2; i += 2) {
      vector<int> v = {1, i, i + 1};
      ans.push_back(v);
    }
    cout << "YES\n" << ans.size() << "\n";
    for (auto& v : ans) {
      for (auto& p : v) cout << p << " ";
      cout << "\n";
    }
  } else {
    if (xr) {
      cout << "NO\n";
      return;
    }
    vector<vector<int> > ans;
    for (int i = 2; i < n; i += 2) {
      vector<int> v = {1, i, i + 1};
      ans.push_back(v);
    }
    for (int i = 2; i <= n - 2; i += 2) {
      vector<int> v = {1, i, i + 1};
      ans.push_back(v);
    }
    cout << "YES\n" << ans.size() << "\n";
    for (auto& v : ans) {
      for (auto& p : v) cout << p << " ";
      cout << "\n";
    }
  }
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t = 1;
  while (t--) solve();
}
