Problem: You are given array a with n integers and m queries. The i-th query is given with three integers li, ri, xi.

For the i-th query find any position pi (li ≤ pi ≤ ri) so that api ≠ xi.

Input

The first line contains two integers n, m (1 ≤ n, m ≤ 2·105) — the number of elements in a and the number of queries.

The second line contains n integers ai (1 ≤ ai ≤ 106) — the elements of the array a.

Each of the next m lines contains three integers li, ri, xi (1 ≤ li ≤ ri ≤ n, 1 ≤ xi ≤ 106) — the parameters of the i-th query.

Output

Print m lines. On the i-th line print integer pi — the position of any number not equal to xi in segment [li, ri] or the value  - 1 if there is no such number.

Examples

Input

6 4
1 2 1 1 3 5
1 4 1
2 6 2
3 4 1
3 4 2


Output

2
6
-1
4

Solution (in JAVA):

Solution:
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author zodiacLeo
 */
public class Main
{
    public static void main(String[] args)
    {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        FastScanner in = new FastScanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskC solver = new TaskC();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskC
    {
        private int n;
        private int[] a;
        private Pair[] st;

        public void solve(int testNumber, FastScanner in, PrintWriter out)
        {
            n = in.nextInt();
            int q = in.nextInt();

            a = new int[n];
            st = new Pair[4 * n + 1];
            Arrays.fill(st, new Pair(Integer.MAX_VALUE, Integer.MIN_VALUE, -1, -1));
            for (int i = 0; i < n; i++)
            {
                a[i] = in.nextInt();
                update(1, 0, n - 1, i, a[i]);
            }
            while (q-- > 0)
            {
                int left = in.nextInt() - 1;
                int right = in.nextInt() - 1;
                int num = in.nextInt();
                Pair p = query(1, 0, n - 1, left, right);
                if (p.max == p.min && p.max == num)
                {
                    out.println(-1);
                } else
                {
                    if (p.min != num)
                    {
                        out.println(p.minIndex + 1);
                    } else
                    {
                        out.println(p.maxIndex + 1);
                    }
                }
            }


        }

        public Pair query(int index, int low, int high, int start, int end)
        {
            if (start > high || end < low)
            {
                return new Pair(Integer.MAX_VALUE, Integer.MIN_VALUE, -1, -1);
            }
            if (start <= low && end >= high)
            {
                return st[index];
            }
            int m = low + high;
            m /= 2;
            int left = 2 * index;
            int right = left + 1;
            Pair leftChild = query(left, low, m, start, end);
            Pair rightChild = query(right, m + 1, high, start, end);
            return combine(leftChild, rightChild);
        }

        public void update(int index, int low, int high, int x, int value)
        {
            if (x < low || x > high)
            {
                return;
            }
            if (x == low && x == high)
            {
                st[index] = new Pair(value, value, x, x);
                return;
            }

            int m = low + high;
            m /= 2;
            int left = 2 * index;
            int right = left + 1;
            update(left, low, m, x, value);
            update(right, m + 1, high, x, value);
            st[index] = combine(st[left], st[right]);
        }

        public Pair combine(Pair leftChild, Pair rightChild)
        {
            int min = Integer.MAX_VALUE;
            int minIndex = -1;
            if (leftChild.min < rightChild.min)
            {
                min = leftChild.min;
                minIndex = leftChild.minIndex;
            } else
            {
                min = rightChild.min;
                minIndex = rightChild.minIndex;
            }

            int max = Integer.MIN_VALUE;
            int maxIndex = -1;
            if (leftChild.max > rightChild.max)
            {
                max = leftChild.max;
                maxIndex = leftChild.maxIndex;
            } else
            {
                max = rightChild.max;
                maxIndex = rightChild.maxIndex;
            }
            return new Pair(min, max, minIndex, maxIndex);

        }

        class Pair
        {
            int min;
            int max;
            int minIndex;
            int maxIndex;

            public Pair(int min, int max, int minIndex, int maxIndex)
            {
                this.min = min;
                this.max = max;
                this.minIndex = minIndex;
                this.maxIndex = maxIndex;
            }

        }

    }

    static class FastScanner
    {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner(InputStream is)
        {
            br = new BufferedReader(new InputStreamReader(is));
        }

        public FastScanner(File f)
        {
            try
            {
                br = new BufferedReader(new FileReader(f));
            } catch (FileNotFoundException e)
            {
                e.printStackTrace();
            }
        }

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

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

    }
}