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.*;
import java.util.*;

import static java.lang.Math.*;


public class Main {
    FastScanner in;
    PrintWriter out;

    static final String FILE = "";

    public void solve() {
        int n = in.nextInt(), m = in.nextInt();
        int pos[] = new int[1_000_005];
        int ans[] = new int[m];
        Arrays.fill(pos, -1);
        TreeSet<Pair> all = new TreeSet<>();
        ArrayList<Pair<Pair<Integer, Integer>, Pair<Integer, Integer>>> list = new ArrayList<>();
        int ms[] = new int[n];
        for (int i = 0; i < n; i++)
            ms[i] = in.nextInt();
        for (int i = 0; i < m; i++) {
            int l = in.nextInt() - 1, r = in.nextInt() - 1, x = in.nextInt();
            list.add(new Pair<>(new Pair<>(l, r), new Pair<>(x, i)));
        }
        Collections.sort(list);
        Collections.reverse(list);

        int curr = n;
        int ch = n;
        for (int i = 0; i < m; i++) {
            int l = list.get(i).a.a;
            int r = list.get(i).a.b;
            int x = list.get(i).b.a;
            int ind = list.get(i).b.b;

            while (curr != l) {
                if (curr < n && curr - 1 >= 0 && ms[curr] != ms[curr - 1]) {
                    ch = curr;
                }
                curr--;
            }

            if (ms[l] != x) {
                ans[ind] = l;
            } else if (ch <= r) {
                ans[ind] = ch;
            } else {
                ans[ind] = -2;
            }
        }

        for (int i = 0; i < m; i++) {
            out.println(ans[i] + 1);
        }
    }

    public void run() {
        if (FILE.equals("")) {
            in = new FastScanner(System.in);
            out = new PrintWriter(System.out);
        } else {
            try {
                in = new FastScanner(new FileInputStream(FILE +
                        ".in"));
                out = new PrintWriter(new FileOutputStream(FILE +
                        ".out"));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
        solve();
        out.close();
    }

    public static void main(String[] args) {
        (new Main()).run();
    }

    class FastScanner {
        BufferedReader br;
        StringTokenizer st;

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

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

        public String nextLine() {
            st = null;
            try {
                return br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
                return "";
            }
        }

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

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

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

        public float nextFloat() {
            return Float.parseFloat(next());
        }
    }

    class Pair<A extends Comparable<A>, B extends Comparable<B>>
            implements Comparable<Pair<A, B>> {
        public A a;
        public B b;

        public Pair(A a, B b) {
            this.a = a;
            this.b = b;
        }

        @Override
        public int compareTo(Pair<A, B> o) {
            if (o == null || o.getClass() != getClass())
                return 1;
            int cmp = a.compareTo(o.a);
            if (cmp == 0)
                return b.compareTo(o.b);
            return cmp;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            Pair<?, ?> pair = (Pair<?, ?>) o;

            if (a != null ? !a.equals(pair.a) : pair.a != null) return
                    false;
            return !(b != null ? !b.equals(pair.b) : pair.b != null);
        }
    }

    class PairInt extends Pair<Integer, Integer> {
        public PairInt(Integer u, Integer v) {
            super(u, v);
        }
    }

    class PairLong extends Pair<Long, Long> {
        public PairLong(Long u, Long v) {
            super(u, v);
        }
    }

}