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.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Random;
import java.util.StringTokenizer;
import java.util.stream.Stream;
import java.util.Iterator;
import java.util.List;


public class Main {




public static void main(String[] args){
 
   new Thread(null, null, "Anshum Gupta", 99999999) {
        public void run() {
            try {
                solve();
            } catch(Exception e) {
                e.printStackTrace();
                System.exit(1);
            }
        }
    }.start();
}
 
static final long INF_LONG = (long)(1e18 + 5), MOD = 998244353; //(long)1e9 + 7
static final int MXN = (int)(1001), MXV = (int)(1e6), log = 18, INF = (int)1e9 + 500;
static boolean[][][]vis;
static ArrayList<ArrayList<Integer>> adj;
static int n, m, q, k, h, w;
static char[] str;
static int[][]a;

public static void solve() throws Exception {
	   // solve the problem here
		s = new MyScanner();
   		out = new MyWriter(new BufferedOutputStream(System.out));
//	   		out = new PrintWriter("output.txt");
        int tc = 1;//s.nextInt();   
    	for(int i=1; i<=tc; i++) {
//        	out.print("Case #" + i + ": ");
    		testcase();
    	}
          
        out.flush();
        out.close();
}


static void testcase() {
	n = s.nextInt();
	int[] a = s.nextIntArray(n);
	int xor = 0;
	for(int x : a) xor ^= x;
	
	if(n % 2 == 0) {
		if(xor != 0) {
			out.println("NO");
			return;
		}
	}
	
	ArrayList<int []> ans = new ArrayList<int[]>();
	for(int i = 0; i < n / 2; i++) {
		int first = 0, second = 2 * i + 1, third = 2 * i + 2;
		if(third >= n) break;
		ans.add(new int[] {first, second, third});
	}
	
	for(int i = 0; i < n / 2; i++) {
		int first = 0, second = 2 * i + 1, third = 2 * i + 2;
		if(third >= n) break;
		ans.add(new int[] {first, second, third});
	}
	
	out.println("YES");
	out.println(ans.size());
	for(int[] op : ans) {
		for(int x : op) {
			out.print((x + 1) + " ");
		}
		out.println();
	}
	
	
	
}







public static MyWriter out;
public static MyScanner s;
static void shuffleArray(int[] a) {
	Random random = new Random();
	for (int i = a.length-1; i > 0; i--) {
		int index = random.nextInt(i + 1);
		int tmp = a[index];
		a[index] = a[i];
		a[i] = tmp;
	}
}
static void shuffleSort(int[] a) {
	shuffleArray(a);
	Arrays.parallelSort(a);
}
static class MyScanner {
 
    BufferedReader br;
    StringTokenizer st;
 
    public MyScanner() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }
    public MyScanner(String fileName) {
    	try {
			br = new BufferedReader(new FileReader(fileName));
		} catch (FileNotFoundException e) {
			e.printStackTrace();
		}
    }
    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()); }
    int[] nextIntArray(int n){
    	int[]a = new int[n];
    	for(int i=0; i<n; i++) {
    		a[i] = this.nextInt();
    	}
    	return a;
    }
    long[] nextlongArray(int n) {
    	long[]a = new long[n];
    	for(int i=0; i<n; i++) {
    		a[i] = this.nextLong();
    	}
    	return a;
    }
    Integer[] nextIntegerArray(int n){
    	Integer[]a = new Integer[n];
    	for(int i=0; i<n; i++) {
    		a[i] = this.nextInt();
    	}
    	return a;
    }
    Long[] nextLongArray(int n) {
    	Long[]a = new Long[n];
    	for(int i=0; i<n; i++) {
    		a[i] = this.nextLong();
    	}
    	return a;
    }
    char[][] next2DCharArray(int n, int m){
    	char[][]arr = new char[n][m];
    	for(int i=0; i<n; i++) {
    		arr[i] = this.next().toCharArray();
    	}
    	return arr;
    }
    ArrayList<ArrayList<Integer>> readUndirectedUnweightedGraph(int n, int m) {
    	ArrayList<ArrayList<Integer>>adj = new ArrayList<ArrayList<Integer>>();
    	for(int i=0; i<=n; i++)adj.add(new ArrayList<Integer>());
    	for(int i=0; i<m; i++) {
    		int u = s.nextInt();
    		int v = s.nextInt();
    		adj.get(u).add(v);
    		adj.get(v).add(u);
    	}
    	return adj;
    }
    ArrayList<ArrayList<Integer>> readDirectedUnweightedGraph(int n, int m) {
    	ArrayList<ArrayList<Integer>>adj = new ArrayList<ArrayList<Integer>>();
    	for(int i=0; i<=n; i++)adj.add(new ArrayList<Integer>());
    	for(int i=0; i<m; i++) {
    		int u = s.nextInt();
    		int v = s.nextInt();
    		adj.get(u).add(v);
    	}
    	return adj;
    }
    String nextLine(){
        String str = "";
        try {
            str = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }
}
 
static class MyWriter extends PrintWriter {
    MyWriter(OutputStream out) {
        super(out);
    }
    void println(int[] x) {
        println(x, " ");
    }
    void println(int[] x, String delimiter) {
        if (x.length > 0) {
            print(x[0]);
            for (int i = 1; i < x.length; i++) {
                print(delimiter);
                print(x[i]);
            }
        }
        println();
    }
    void println(long[] x) {
        println(x, " ");
    }
    void println(long[] x, String delimiter) {
        if (x.length > 0) {
            print(x[0]);
            for (int i = 1; i < x.length; i++) {
                print(delimiter);
                print(x[i]);
            }
        }
        println();
    }
    void println(Iterable<?> iterable) {
        println(iterable, " ");
    }
    void println(Iterable<?> iterable, String delimiter) {
        Iterator<?> i = iterable.iterator();
        if (i.hasNext()) {
            print(i.next());
            while (i.hasNext()) {
                print(delimiter);
                print(i.next());
            }
        }
        println();
    }
    void printLines(int[] x) {
        println(x, System.lineSeparator());
    }
    void printLines(long[] x) {
        println(x, System.lineSeparator());
    }
    void printLines(Iterable<?> iterable) {
        println(iterable, System.lineSeparator());
    }
}
 
}