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.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class P622C {
  InputStream is;
  PrintWriter out;
  String INPUT = "6 4\n" +
      "1 2 1 1 3 5\n" +
      "1 4 1\n" +
      "2 6 2\n" +
      "3 4 1\n" +
      "3 4 2";
  
  void solve() {
    int n = ni();
    int m = ni();

    int[] a = new int[n];
    int[] end = new int[n];
    for (int i = 0; i < n; i++) {
      a[i] = ni();
    }
    end[n - 1] = n - 1;
    for (int i = n - 1; i > 0; i--) {
      if (a[i] == a[i - 1]) {
        end[i - 1] = end[i];
      } else {
        end[i - 1] = i - 1;
      }
    }
    for (int i = 0; i < m; i++) {
      int l = ni() - 1;
      int r = ni() - 1;
      int x = ni();

      while (l <= r && l < n) {
        if (a[l] != x) {
          out.println(l + 1);
          break;
        }
        l = end[l] + 1;
      }
      if (l > r) {
        out.println(-1);
      }
    }
    out.flush();
  }
  
  public static void main(String[] args) throws Exception {
    new P622C().run();
  }
  
  void run() throws Exception {
    is = oj ? System.in : new ByteArrayInputStream(INPUT.getBytes());
    out = new PrintWriter(System.out);
  
    long s = System.currentTimeMillis();
    solve();
    out.flush();
    tr(System.currentTimeMillis() - s + "ms");
  }
  
  private byte[] inbuf = new byte[1024];
  private int lenbuf = 0, ptrbuf = 0;
  
  private int readByte() {
    if (lenbuf == -1)
      throw new InputMismatchException();
    if (ptrbuf >= lenbuf) {
      ptrbuf = 0;
      try {
        lenbuf = is.read(inbuf);
      } catch (IOException e) {
        throw new InputMismatchException();
      }
      if (lenbuf <= 0)
        return -1;
    }
    return inbuf[ptrbuf++];
  }
  
  private boolean isSpaceChar(int c) {
    return !(c >= 33 && c <= 126);
  }
  
  private int skip() {
    int b;
    while ((b = readByte()) != -1 && isSpaceChar(b))
      ;
    return b;
  }
  
  private double nd() {
    return Double.parseDouble(ns());
  }
  
  private char nc() {
    return (char) skip();
  }
  
  private String ns() {
    int b = skip();
    StringBuilder sb = new StringBuilder();
    while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
      sb.appendCodePoint(b);
      b = readByte();
    }
    return sb.toString();
  }
  
  private char[] ns(int n) {
    char[] buf = new char[n];
    int b = skip(), p = 0;
    while (p < n && !(isSpaceChar(b))) {
      buf[p++] = (char) b;
      b = readByte();
    }
    return n == p ? buf : Arrays.copyOf(buf, p);
  }
  
  private char[][] nm(int n, int m) {
    char[][] map = new char[n][];
    for (int i = 0; i < n; i++)
      map[i] = ns(m);
    return map;
  }
  
  private int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }
  
  private int ni() {
    int num = 0, b;
    boolean minus = false;
    while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
      ;
    if (b == '-') {
      minus = true;
      b = readByte();
    }
  
    while (true) {
      if (b >= '0' && b <= '9') {
        num = num * 10 + (b - '0');
      } else {
        return minus ? -num : num;
      }
      b = readByte();
    }
  }
  
  private long nl() {
    long num = 0;
    int b;
    boolean minus = false;
    while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
      ;
    if (b == '-') {
      minus = true;
      b = readByte();
    }
  
    while (true) {
      if (b >= '0' && b <= '9') {
        num = num * 10 + (b - '0');
      } else {
        return minus ? -num : num;
      }
      b = readByte();
    }
  }
  
  private boolean oj = System.getProperty("ONLINE_JUDGE") != null;
  
  private void tr(Object... o) {
    if (!oj)
      System.out.println(Arrays.deepToString(o));
  }
}