Problem: Ksenia has an array a consisting of n positive integers a_1, a_2, …, a_n. 

In one operation she can do the following: 

  * choose three distinct indices i, j, k, and then 
  * change all of a_i, a_j, a_k to a_i ⊕ a_j ⊕ a_k simultaneously, where ⊕ denotes the [bitwise XOR operation](https://en.wikipedia.org/wiki/Bitwise_operation#XOR). 



She wants to make all a_i equal in at most n operations, or to determine that it is impossible to do so. She wouldn't ask for your help, but please, help her!

Input

The first line contains one integer n (3 ≤ n ≤ 10^5) — the length of a.

The second line contains n integers, a_1, a_2, …, a_n (1 ≤ a_i ≤ 10^9) — elements of a.

Output

Print YES or NO in the first line depending on whether it is possible to make all elements equal in at most n operations.

If it is possible, print an integer m (0 ≤ m ≤ n), which denotes the number of operations you do.

In each of the next m lines, print three distinct integers i, j, k, representing one operation. 

If there are many such operation sequences possible, print any. Note that you do not have to minimize the number of operations.

Examples

Input


5
4 2 1 7 2


Output


YES
1
1 3 4

Input


4
10 4 49 22


Output


NO

Note

In the first example, the array becomes [4 ⊕ 1 ⊕ 7, 2, 4 ⊕ 1 ⊕ 7, 4 ⊕ 1 ⊕ 7, 2] = [2, 2, 2, 2, 2].

Solution (in JAVA):

Solution:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Locale;
import java.util.Set;
import java.util.StringTokenizer;

public class A {
    private String nextToken() throws IOException {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
        }
        return tokenizer.nextToken();
    }

    private int nextInt() throws NumberFormatException, IOException {
        return Integer.parseInt(nextToken());
    }

    private double nextDouble() throws NumberFormatException, IOException {
        return Double.parseDouble(nextToken());
    }

    private long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }

    private void print(Object o) {
        writer.print(o);
    }

    private void println(Object o) {
        writer.println(o);
    }

    private void printf(String format, Object... o) {
        writer.printf(format, o);
    }

    public static void main(String[] args) {
        long time = System.currentTimeMillis();
        Locale.setDefault(Locale.US);
        new A().run();
        System.err.printf("%.3f\n", 1e-3 * (System.currentTimeMillis() - time));
    }

    BufferedReader reader;
    StringTokenizer tokenizer;
    PrintWriter writer;

    private void run() {
        try {
            reader = new BufferedReader(new InputStreamReader(System.in));
            writer = new PrintWriter(System.out);
            solve();
            reader.close();
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
            System.exit(13);
        }
    }

    private void solve() throws IOException {
        int n = nextInt();
        int[] a = new int[n];
        for (int i = 0; i < n; i++) {
            a[i] = nextInt();
        }

        List<List<Integer>> result = new ArrayList<>();

        for (int i = 0; i < n - 2; i += 2) {
            int p = a[i] ^ a[i + 1] ^ a[i + 2];
            a[i] = a[i + 1] = a[i + 2] = p;
            List<Integer> row = new ArrayList<>();
            row.add(i + 1);
            row.add(i + 2);
            row.add(i + 3);
            result.add(row);
        }

        int last = n - 1;
        if (n % 2 == 0) {
            last--;
        }

        for (int i = last - 3; i > 0; i -= 2) {
            List<Integer> row = new ArrayList<>();
            row.add(last + 1);
            row.add(i + 1);
            row.add(i);
            result.add(row);
        }

        if (a[last] != a[n - 1]) {
            println("NO");
        } else {
            println("YES");
            println(result.size());
            for (List<Integer> row: result) {
                for (int v: row) {
                    print(v + " ");
                }
                println("");
            }
        }
    }
}