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.util.*;
import static java.lang.Math.*;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class WaterLevel {
    public static void main(String[] args) throws IOException {
        // InputStream inputStream = new FileInputStream("input.txt");
        // OutputStream outputStream = new FileOutputStream("output.txt");
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }
    static class TaskA {
        long mod = (long)(998244353);
        long fact[];
        int depth[];
        int parentTable[][];
        int degree[];
        ArrayList<Integer> leaves;
        int max = Integer.MIN_VALUE;
        int min = Integer.MAX_VALUE;
        int diam = 0;

        int res = 0;

        public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {
            while(testNumber-->0){
                int n = in.nextInt();
                long a[] = new long[n];
                long x = 0;
                for(int i=0;i<n;i++){
                    a[i] = in.nextLong();
                    x^=a[i];
                }
                ArrayList<long[]> ans = new ArrayList<>();    
                if(n%2 == 1){
                    for(int i=1;i<n;i+=2){
                        long y[] = new long[3];
                        for(int j=i;j<i+3;j++){
                            y[j-i] = j;
                        }
                        ans.add(y);
                    }
                    for(int i=1;i<=n-3;i+=2){
                        ans.add(new long[]{i , i+1 , n});
                    }
                }
                else if(n%2 == 0){
                    if(x != 0){
                        out.println("NO");
                        continue;
                    }
                    else{
                        for(int i=1;i<n-1;i+=2){
                            long y[] = new long[3];
                            for(int j=i;j<i+3;j++){
                                y[j-i] = j;
                            }
                            ans.add(y);
                        }
                        for(int i=1;i<=n-4;i+=2){
                            ans.add(new long[]{i , i+1 , n-1});
                        }
                    }
                }
                out.println("YES");
                out.println(ans.size());
                for(long i[] : ans){
                    for(int j=0;j<3;j++)
                        out.print(i[j] + " ");
                    out.println();
                }
            }
        }

        public int distance(ArrayList<ArrayList<Integer>> a , int u , int v){
            return depth[u]+depth[v] - 2*depth[lca(a , u , v)];
        }

        public int lca(ArrayList<ArrayList<Integer>> a , int u , int v){
            if(depth[v]<depth[u]){
                int x = u;
                u = v;
                v = x;
            }
            int diff = depth[v] - depth[u];
            for(int i=0;i<parentTable[v].length;i++){
                // checking whether the ith bit is set in the diff variable
                if(((diff>>i)&1) == 1)
                    v = parentTable[v][i];
            }
            if(v == u)
                return v;
            for(int i=parentTable[v].length-1;i>=0;i--){
                if(parentTable[u][i] != parentTable[v][i]){
                    v = parentTable[v][i];
                    u = parentTable[u][i];
                }
            }
            return parentTable[u][0];
        }
        

        public int[][] multiply(int a[][] , int b[][]){
            int c[][] = new int[a.length][b[0].length];
            for(int i=0;i<a.length;i++){
                for(int j=0;j<b[0].length;j++){
                    for(int k=0;k<b.length;k++)
                        c[i][j] += a[i][k]*b[k][j];
                }
            }
            return c;
        }

        public int[][] multiply(int a[][] , int b[][] , int mod){
            int c[][] = new int[a.length][b[0].length];
            for(int i=0;i<a.length;i++){
                for(int j=0;j<b[0].length;j++){
                    for(int k=0;k<b.length;k++){
                        c[i][j] += a[i][k]*b[k][j];
                        c[i][j]%=mod;
                    }
                }
            }
            return c;
        }

        public int[][] pow(int a[][] , long b){
            int res[][] = new int[a.length][a[0].length];
            for(int i=0;i<a.length;i++)
                res[i][i] = 1;
            while(b>0){
                if((b&1) == 1)
                    res = multiply(res , a , 10);
                a = multiply(a , a , 10);
                b>>=1;
            }
            return res;
        }

        

        // for the min max problems
        public void build(int lookup[][] , int arr[], int n) { 
            for (int i = 0; i < n; i++) 
                lookup[i][0] = arr[i]; 
            for (int j = 1; (1 << j) <= n; j++) { 
                for (int i = 0; (i + (1 << j) - 1) < n; i++) { 
                    if (lookup[i][j - 1] > lookup[i + (1 << (j - 1))][j - 1]) 
                        lookup[i][j] = lookup[i][j - 1]; 
                    else
                        lookup[i][j] = lookup[i + (1 << (j - 1))][j - 1]; 
                } 
            } 
        }
        public int query(int lookup[][] , int L, int R) { 
            int j = (int)(Math.log(R - L + 1)/Math.log(2)); 
            if (lookup[L][j] >= lookup[R - (1 << j) + 1][j]) 
                return lookup[L][j]; 
            else
                return lookup[R - (1 << j) + 1][j]; 
        }

        // for printing purposes
        public void print1d(int a[] , PrintWriter out){
            for(int i=0;i<a.length;i++)
                out.print(a[i] + " ");
            out.println();
        }
        public void print1d(long a[] , PrintWriter out){
            for(int i=0;i<a.length;i++)
                out.print(a[i] + " ");
            out.println();
        }
        public void print2d(int a[][] , PrintWriter out){
            for(int i=0;i<a.length;i++){
                for(int j=0;j<a[i].length;j++)
                    out.print(a[i][j] + " ");
                out.println();
            }
            // out.println();
        }
        public void print2d(long a[][] , PrintWriter out){
            for(int i=0;i<a.length;i++){
                for(int j=0;j<a[i].length;j++)
                    out.print(a[i][j] + " ");
                out.println();
            }
            // out.println();
        }


        public void sieve(int a[]){
            a[0] = a[1] = 1;
            int i;
            for(i=2;i*i<=a.length;i++){
                if(a[i] != 0)
                    continue;
                a[i] = i;
                for(int k = (i)*(i);k<a.length;k+=i){
                    if(a[k] != 0)
                        continue;
                    a[k] = i;
                }
            }
        }

        public long nCrPFermet(int n , int r , long p){
            if(r==0)
                return 1l;
            // long fact[] = new long[n+1];
            // fact[0] = 1;
            // for(int i=1;i<=n;i++)
            //     fact[i] = (i*fact[i-1])%p;
            long modInverseR = pow(fact[r] , p-2 , p);
            long modInverseNR = pow(fact[n-r] , p-2 , p);
            long w = (((fact[n]*modInverseR)%p)*modInverseNR)%p;
            return w;
        }
        public long pow(long a, long b, long m) {
            a %= m;
            long res = 1;
            while (b > 0) {
                long x = b&1;
                if (x == 1)
                    res = res * a % m;
                a = a * a % m;
                b >>= 1;
            }
            return res;
        }
        public long pow(long a, long b) {
            long res = 1;
            while (b > 0) {
                long x = b&1;
                if (x == 1)
                    res = res * a;
                a = a * a;
                b >>= 1;
            }
            return res;
        }
        public void sortedArrayToBST(TreeSet<Integer> a , int start, int end) { 
            if (start > end) {
                return;
            }
            int mid = (start + end) / 2;
            a.add(mid);
            sortedArrayToBST(a, start, mid - 1);
            sortedArrayToBST(a, mid + 1, end); 
        }
        class Combine{
            int value;
            int delete;
            Combine(int val , int delete){
                this.value = val;
                this.delete = delete;
            }
        }
        class Sort2 implements Comparator<Combine>{
            public int compare(Combine a , Combine b){
                if(a.value > b.value)
                    return 1;
                else if(a.value == b.value && a.delete>b.delete)
                    return 1;
                else if(a.value == b.value && a.delete == b.delete)
                    return 0;
                return -1;
            }
        }
        public int lowerLastBound(ArrayList<Integer> a , int x){
            int l = 0;
            int r = a.size()-1;
            if(a.get(l)>=x)
                return -1;
            if(a.get(r)<x)
                return r;
            int mid = -1;
            while(l<=r){
                mid = (l+r)/2;
                if(a.get(mid) == x && a.get(mid-1)<x)
                    return mid-1;
                else if(a.get(mid)>=x)
                    r = mid-1;
                else if(a.get(mid)<x && a.get(mid+1)>=x)
                    return mid;
                else if(a.get(mid)<x && a.get(mid+1)<x)
                    l = mid+1;
            }
            return mid;
        }
        public int upperFirstBound(ArrayList<Integer> a , int x){
            int l = 0;
            int r = a.size()-1;
            if(a.get(l)>x)
                return l;
            if(a.get(r)<=x)
                return r+1;
            int mid = -1;
            while(l<=r){
                mid = (l+r)/2;
                if(a.get(mid) == x && a.get(mid+1)>x)
                    return mid+1;
                else if(a.get(mid)<=x)
                    l = mid+1;
                else if(a.get(mid)>x && a.get(mid-1)<=x)
                    return mid;
                else if(a.get(mid)>x && a.get(mid-1)>x)
                    r = mid-1;
            }
            return mid;
        }
        public int lowerLastBound(long a[] , long x){
            int l = 0;
            int r = a.length-1;
            if(a[l]>=x)
                return -1;
            if(a[r]<x)
                return r;
            int mid = -1;
            while(l<=r){
                mid = (l+r)/2;
                if(a[mid] == x && a[mid-1]<x)
                    return mid-1;
                else if(a[mid]>=x)
                    r = mid-1;
                else if(a[mid]<x && a[mid+1]>=x)
                    return mid;
                else if(a[mid]<x && a[mid+1]<x)
                    l = mid+1;
            }
            return mid;
        }
        public int upperFirstBound(long a[] , long x){
            int l = 0;
            int r = a.length-1;
            if(a[l]>x)
                return l;
            if(a[r]<=x)
                return r+1;
            int mid = -1;
            while(l<=r){
                mid = (l+r)/2;
                if(a[mid] == x && a[mid+1]>x)
                    return mid+1;
                else if(a[mid]<=x)
                    l = mid+1;
                else if(a[mid]>x && a[mid-1]<=x)
                    return mid;
                else if(a[mid]>x && a[mid-1]>x)
                    r = mid-1;
            }
            return mid;
        }
        public long log(float number , int base){
            return (long) Math.ceil((Math.log(number) / Math.log(base)) + 1e-9);
        }
        public long gcd(long a , long b){
            if(a<b){
                long c = b;
                b = a;
                a = c;
            }
            while(b!=0){
                long c = a;
                a = b;
                b = c%a;
            }
            return a;
        }
        public long[] gcdEx(long p, long q) {
            if (q == 0)
                return new long[] { p, 1, 0 };
            long[] vals = gcdEx(q, p % q);
            long d = vals[0];
            long a = vals[2];
            long b = vals[1] - (p / q) * vals[2];
            // 0->gcd 1->xValue 2->yValue
            return new long[] { d, a, b };
        }
        public void sievePhi(int a[]){
            a[0] = 0;
            a[1] = 1;
            for(int i=2;i<a.length;i++)
                a[i] = i-1;
            for(int i=2;i<a.length;i++)
                for(int j = 2*i;j<a.length;j+=i)
                    a[j] -= a[i];
        }
        public void lcmSum(long a[]){
            int sievePhi[] = new int[(int)1e6 + 1];
            sievePhi(sievePhi);
            a[0] = 0;
            for(int i=1;i<a.length;i++)
                for(int j = i;j<a.length;j+=i)
                    a[j] += (long)i*sievePhi[i];
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

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

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

    }
}