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 java.util.stream.Collectors;


public class Main {
    void solve() {
        int n = in.nextInt();
        int[] a = in.nextInts(n);
        List<List<Integer>> ans = new ArrayList<>();
        for (int i = 0; i + 2 < n; i += 2) {
            ans.add(Arrays.asList(i + 1, i + 2, i + 3));
            int tmp = a[i] ^ a[i + 1] ^ a[i + 2];
            a[i] = tmp;
            a[i + 1] = tmp;
            a[i + 2] = tmp;
        }
        if (a[n - 2] != a[n - 1]) {
            out.println("NO");
            return;
        }
        out.println("YES");
        for (int i = 0; i + 2 < n; i += 2) {
            ans.add(Arrays.asList(i + 1, i + 2, n));
        }
        out.println(ans.size());
        for (List<Integer> el : ans) {
            out.println(el.get(0) + " " + el.get(1) + " " + el.get(2));
        }
    }

    static final boolean MULTI_TEST = false;

    // --------------------------------------------------------------------------------------------------------------
    // --------------------------------------------------HELPER------------------------------------------------------
    // --------------------------------------------------------------------------------------------------------------

    static final int MOD = 1000000007;

    void run() {
        if (MULTI_TEST) {
            int t = in.nextInt();
            for (int i = 0; i < t; i++) {
                solve();
            }
        } else {
            solve();
        }
    }

    // --------------------ALGORITHM-------------------------

    public void sort(int[] arr) {
        List<Integer> tmp = Arrays.stream(arr).boxed().sorted().collect(Collectors.toList());
        for (int i = 0; i < arr.length; i++) {
            arr[i] = tmp.get(i);
        }
    }

    public void sortRev(int[] arr) {
        List<Integer> tmp = Arrays.stream(arr).boxed().sorted(Comparator.comparing((Integer x) -> x).reversed())
                .collect(Collectors.toList());
        for (int i = 0; i < arr.length; i++) {
            arr[i] = tmp.get(i);
        }
    }

    // --------------------SCANNER-------------------------
    public static class MyScanner {
        BufferedReader br;
        StringTokenizer st;

        public MyScanner(String fileName) {
            if (fileName != null) {
                try {
                    br = new BufferedReader(new FileReader(fileName));
                } catch (FileNotFoundException e) {
                    throw new RuntimeException(e);
                }
            } else {
                br = new BufferedReader(new InputStreamReader(System.in));
            }
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                st = new StringTokenizer(nextLine());
            }
            return st.nextToken();
        }

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

        int[] nextInts(int n) {
            int[] arr = new int[n];
            for (int i = 0; i < n; i++) {
                arr[i] = nextInt();
            }
            return arr;
        }

        boolean[] nextLineBools() {
            String line = nextLine();
            int n = line.length();
            boolean[] booleans = new boolean[n];
            for (int i = 0; i < n; i++) {
                booleans[i] = line.charAt(i) == '1';
            }
            return booleans;
        }

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

        public long[] nextLongs(int n) {
            long[] arr = new long[n];
            for (int i = 0; i < n; i++) {
                arr[i] = nextLong();
            }
            return arr;
        }

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

        String nextLine() {
            try {
                String line = br.readLine();
                if (line == null) {
                    throw new RuntimeException("empty line");
                }
                return line;
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }

    }

    // --------------------WRITER-------------------------
    public static class MyWriter extends PrintWriter {

        public static MyWriter of(String fileName) {
            if (fileName != null) {
                try {
                    return new MyWriter(new FileWriter(fileName));
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } else {
                return new MyWriter(new BufferedOutputStream(System.out));
            }
        }

        public MyWriter(FileWriter fileWriter) {
            super(fileWriter);
        }

        public MyWriter(OutputStream out) {
            super(out);
        }

        void println(int[] arr) {
            String line = Arrays.stream(arr).mapToObj(String::valueOf).collect(Collectors.joining(" "));
            println(line);
        }
    }

    // -----------------------BENCHMARK-------------------------
    public static class Benchmark {
        long time;

        public void reset() {
            time = System.currentTimeMillis();
        }

        public long calc() {
            long curTime = System.currentTimeMillis();
            long tmp = curTime - time;
            time = curTime;
            return tmp;
        }

    }


    // --------------------MAIN-------------------------

    public MyScanner in;
    public MyWriter out;
    public Benchmark bm;

    /**
     * run as `java Main`, `java Main input.txt' or `java Main input.txt output.txt'
     * add `-Xss256m` to increase stack size
     */
    public static void main(String[] args) {
        Main m = new Main();
        m.in = new MyScanner(args.length > 0 ? args[0] : null);
        m.out = MyWriter.of(args.length > 1 ? args[1] : null);
        m.bm = new Benchmark();
        m.run();
        m.out.close();
    }
}