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.awt.*;
import java.io.*;
import java.util.*;
import java.util.List;
import java.util.concurrent.LinkedBlockingQueue;

public class Coding {

    private static BufferedReader bi = new BufferedReader(new InputStreamReader(System.in));
    private static BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(System.out));

    public static void main(String[] args) {
        try {
            run();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static class Sol {
        int i,j,k;
        public Sol(int i, int j, int k) {
            this.i = i;
            this.j = j;
            this.k = k;
        }
    }

    public static void run() throws Exception {
        InputModule inp = new InputModule();
        OutputModule out = new OutputModule();
        int t = 1;
        while (t > 0) {
            int n = inp.cinInt();
            int totXor = 0;
            int[] ar = inp.cinIntArray(n);
            for(int i=0;i<n;++i) totXor = totXor^ar[i];
            List<Sol> ans = new ArrayList<>();
            if (n%2==1) {
                for (int i=0;i<n-2;i+=2) {
                    ans.add(new Sol(i , i+1, i+2));
                }
                for(int i=0;i<n-2;i+=2) {
                    ans.add(new Sol(i , i+1, n-1));
                }
            } else {
                if (totXor!=0) {
                    out.printString("NO");
                    t--;
                    continue;
                }
                for (int i=0;i<n-2;i+=2) {
                    ans.add(new Sol(i , i+1, i+2));
                }
                for(int i=0;i<n-2;i+=2) {
                    ans.add(new Sol(i , i+1, n-1));
                }
            }
            out.printString("YES");
            out.printInt(ans.size());
            for(int i=0;i<ans.size();++i) {
                writer.append((ans.get(i).i+1) + " " + (ans.get(i).j+1) + " " + (ans.get(i).k+1) + "\n");
            }
            writer.flush();
            t--;
        }
    }


    private static class InputModule {
        private int cinInt() throws Exception {
            return Integer.parseInt(bi.readLine().split(" ")[0].trim());
        }

        private long cinLong() throws Exception {
            return Long.parseLong(bi.readLine().split(" ")[0].trim());
        }

        private Double cinDouble() throws Exception {
            return Double.parseDouble(bi.readLine().split(" ")[0].trim());
        }

        private String cinString() throws Exception {
            return bi.readLine();
        }

        private int[] cinIntArray(int n) throws Exception {
            String input = bi.readLine();
            String[] values = input.split(" ");
            int[] ar = new int[n];
            for (int i = 0; i < n; ++i) {
              ar[i] = Integer.parseInt(values[i]);
            }
            return ar;
        }

        private int[] cinIntArray() throws Exception {
            String input = bi.readLine();
            String[] values = input.split(" ");
            int[] ar = new int[values.length];
            for (int i = 0; i < values.length; ++i) {
                ar[i] = Integer.parseInt(values[i]);
            }
            return ar;
        }

        private long[] cinLongArray(int n) throws Exception {
            String input = bi.readLine();
            String[] values = input.split(" ");
            long[] ar = new long[n];
            for (int i = 0; i < n; ++i) {
                ar[i] = Long.parseLong(values[i]);
            }
            return ar;
        }

        private String[] cinStringArray(int n) throws Exception {
            return bi.readLine().split(" ");
        }
    }

    private static class OutputModule {
        private void printInt(int ans) throws Exception {
            writer.append(ans + "\n");
            writer.flush();
        }

        private void printLong(long ans) throws Exception {
            writer.append(ans + "\n");
            writer.flush();
        }

        private void printDouble(Double ans) throws Exception {
            writer.append(String.format("%.10f", ans));
            writer.append("\n");
            writer.flush();
        }

        private void printString(String ans) throws Exception {
            writer.append(ans + "\n");
            writer.flush();
        }

        private void printIntArray(int[] ans) throws Exception {
            for (int i = 0; i < ans.length; ++i) {
                writer.append(ans[i] + " ");
            }
            writer.append("\n");
            writer.flush();
        }

        private void printLongArray(long[] ans) throws Exception {
            for (int i = 0; i < ans.length; ++i) {
                writer.append(ans[i] + " ");
            }
            writer.append("\n");
            writer.flush();
        }

        private void printIntMatrix(int[][] mat, int n, int m) throws Exception {
            for (int i = 0; i < n; ++i) {
                for (int j = 0; j < m; ++j) {
                    writer.append(mat[i][j] + " ");
                }
                writer.append("\n");
            }
            writer.flush();
        }

        private void printLongMatrix(long[][] mat, int n, int m) throws Exception {
            for (int i = 0; i < n; ++i) {
                for (int j = 0; j < m; ++j) {
                    writer.append(mat[i][j] + " ");
                }
                writer.append("\n");
            }
            writer.flush();
        }

        private void printPoint(Point p) throws Exception {
            writer.append(p.x + " " + p.y + "\n");
            writer.flush();
        }

        private void printPoints(List<Point> p) throws Exception {
            for (Point pp : p) {
                writer.append(pp.x + " " + pp.y + "\n");
            }
            writer.flush();
        }
    }
}