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.*;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.*;

public class D {
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }

    static FastReader s = new FastReader();
    static PrintWriter out = new PrintWriter(System.out);

    private static int[] rai(int n) {
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = s.nextInt();
        }
        return arr;
    }

    private static int[][] rai(int n, int m) {
        int[][] arr = new int[n][m];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                arr[i][j] = s.nextInt();
            }
        }
        return arr;
    }

    private static long[] ral(int n) {
        long[] arr = new long[n];
        for (int i = 0; i < n; i++) {
            arr[i] = s.nextLong();
        }
        return arr;
    }

    private static long[][] ral(int n, int m) {
        long[][] arr = new long[n][m];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < m; j++) {
                arr[i][j] = s.nextLong();
            }
        }
        return arr;
    }

    private static int ri() {
        return s.nextInt();
    }

    private static long rl() {
        return s.nextLong();
    }

    private static String rs() {
        return s.next();
    }


    static boolean check1(int[] arr,int n)
    {
        int prev_ind=0;
        int ind=0;
//        int min=arr[0];
//        int sub=0;
        while(ind<n)
        {
            boolean flag=true;
            for(int i=ind+1;i<n;i++)
            {
                if(arr[i]<arr[i-1])
                {
                    ind=i-1;
                    flag=false;
                    break;
                }
            }
            if(flag)
            {
//                System.out.println("yoyo");
                break;
            }
//            System.out.println(ind);
            if(arr[ind]-arr[ind+1]>(arr[prev_ind]))
            {
                return false;
            }
            else
            {
                for(int i=prev_ind;i<=ind;i++)
                {
                    arr[i]-=(arr[ind]-arr[ind+1]);
                    if(arr[i]==0)
                    {
                        prev_ind++;
                    }
                }


            }
        }
        return true;
    }

    public static void main(String[] args) {
        StringBuilder ans = new StringBuilder();
//        int t = ri();
        int t=1;
        while(t-- >0) {
            int n=ri();
            int[] arr=rai(n);
            if(n%2==0)
            {
                int tot=0;
                for(int i:arr)
                {
                    tot^=i;
                }
                if(tot!=0)
                {
                    ans.append("NO\n");
                    continue;
                }
                n--;

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

            StringBuilder res=new StringBuilder();
            int count=0;
            ans.append("YES\n");
            for(int i=1;i<n;i+=2)
            {
                count++;
                res.append(i).append(" ").append(i+1).append(" ").append(last).append("\n");
            }
            for(int i=1;i<n;i+=2)
            {
                count++;
                res.append(i).append(" ").append(i+1).append(" ").append(last).append("\n");
            }
            ans.append(count).append("\n");
            ans.append(res.toString());
        }
        out.print(ans.toString());
        out.flush();

    }



}