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.math.BigDecimal;
import java.math.BigInteger;
import java.math.RoundingMode;
import java.util.*;
import java.util.concurrent.LinkedBlockingDeque;


public class scratch_25 {
    // int count=0;
    //static long count=0;
    static class Reader {
        static BufferedReader reader;
        static StringTokenizer tokenizer;

        /**
         * call this method to initialize reader for InputStream
         */
        static void init(InputStream input) {
            reader = new BufferedReader(
                    new InputStreamReader(input));
            tokenizer = new StringTokenizer("");
        }

        /**
         * get next word
         */
        static String next() throws IOException {
            while (!tokenizer.hasMoreTokens()) {
                //TODO add check for eof if necessary
                tokenizer = new StringTokenizer(
                        reader.readLine());
            }
            return tokenizer.nextToken();
        }

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

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

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





    static class Pair implements Comparable<Pair>{
        long x;
        long y;
        public Pair(long x,long y){
            this.x=x;
            this.y=y;
        }
        @Override
        public int compareTo(Pair o){
            return (int)this.x-(int)o.x;


        }
        @Override
        public boolean equals(Object me) {
            Pair binMe = (Pair)me;
            if(this.x==binMe.x && this.y==binMe.y)
                return true;
            else
                return false;
        }

        @Override
        public int hashCode() {
            return (int)this.x + (int)this.y;
        }

        @Override
        public String toString() {
            return x+" "+y;
        }


    }







    public static void main(String[] args)  throws IOException {
        Reader.init(System.in);
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
        int n= Reader.nextInt();
        long arr[]= new long[n];
        for (int i = 0; i <n ; i++) {
            arr[i]= Reader.nextLong();
        }
        if(n%2!=0){

            out.append("YES"+"\n");
            out.append((n-2)+"\n");
            int p1=2;
            int p2=p1+1;
            while(p2<=n){
                out.append(1+" "+p1+" "+p2+"\n");
                p1+=2;
                p2+=2;
            }
             p1=2;
            p2=p1+1;
            while(p1<=n-2){
                out.append(1+" "+p1+" "+p2+"\n");
                p1+=2;
                p2+=2;
            }}


            if(n%2==0){
                long val=0;
                for (int i = 0; i <n ; i++) {
                    val=val^arr[i];
                }
                if(val!=0){
                    out.append("NO"+"\n");
                }
                else{
                    out.append("YES"+"\n");
                    out.append((n-3)+"\n");
                    int p1=2;
                    int p2=p1+1;
                    while(p1<n){
                        out.append(1+" "+p1+" "+p2+"\n");
                        p1+=2;
                        p2+=2;
                    }
                     p1=2;
                    p2=p1+1;
                    while(p1<n-2){
                        out.append(1+" "+p1+" "+p2+"\n");
                        p1+=2;
                        p2+=2;
                    }















                }





            }






        out.flush();
        out.close();



    }


    public static void bfs(int x,int y, int n,char [][]ar,int done[][]){
        LinkedList<int[]>stk= new LinkedList<>();
        int a[]={x,y};
        stk.addFirst(a);
        while(!stk.isEmpty()){
            int b[]=stk.removeFirst();
            if(done[b[0]][b[1]]==1){
                continue;
            }
            done[b[0]][b[1]]=1;
            int arr[][]={{1,0},{-1,0},{0,1},{0,-1}};
            for (int i = 0; i <arr.length ; i++) {
                if(!(b[0]+arr[i][0]>=n || b[1]+arr[i][1]>=n || b[0]+arr[i][0]<0 || b[1]+arr[i][1]<0 ||  ar[b[0]+arr[i][0]][b[1]+arr[i][1]]=='1')){
                    int r[]= {b[0]+arr[i][0], b[1]+arr[i][1]};
                    stk.addFirst(r);
                    // continue;
                }
            }
        }
    }




























    public static ArrayList<Integer> Sieve(int n) {
        boolean arr[]= new boolean [n+1];
        Arrays.fill(arr,true);
        arr[0]=false;
        arr[1]=false;
        for (int i = 2; i*i <=n ; i++) {
            if(arr[i]){
                for (int j = 2; j <=n/i ; j++) {
                    int u= i*j;
                    arr[u]=false;
                }}
        }
        ArrayList<Integer> ans= new ArrayList<>();
        for (int i = 0; i <n+1 ; i++) {
            if(arr[i]){
                ans.add(i);
            }
        }
        return ans;
    }




    static long power( long x, long y, long p)
    {

        long res = 1;


        x = x % p;

        if (x == 0) return 0;

        while (y > 0)
        {

            if((y & 1)==1)
                res = (res * x) % p;


            y = y >> 1;
            x = (x * x) % p;
        }
        return res;
    }

    public static long ceil_div(long a, long b){
        return (a+b-1)/b;
    }

    static long gcd(long a, long b)
    {
        if (a == 0)
            return b;
        return gcd(b % a, a);
    }

    static long lcm(long a, long b)
    {
        return (a*b)/gcd(a, b);
    }

}