Problem: Olesya loves numbers consisting of n digits, and Rodion only likes numbers that are divisible by t. Find some number that satisfies both of them.

Your task is: given the n and t print an integer strictly larger than zero consisting of n digits that is divisible by t. If such number doesn't exist, print  - 1.

Input

The single line contains two numbers, n and t (1 ≤ n ≤ 100, 2 ≤ t ≤ 10) — the length of the number and the number it should be divisible by.

Output

Print one such positive number without leading zeroes, — the answer to the problem, or  - 1, if such number doesn't exist. If there are multiple possible answers, you are allowed to print any of them.

Examples

Input

3 2


Output

712

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
int s[110];
int main() {
  int n, t;
  scanf("%d%d", &n, &t);
  if (n == 1) {
    if (t == 10)
      puts("-1");
    else
      printf("%d\n", t);
  } else {
    s[0] = 1;
    if (t == 3 || t == 4 || t == 6) s[1] = 2;
    if (t == 7) s[1] = 4;
    if (t == 8) s[1] = 6;
    if (t == 9) s[1] = 8;
    for (int i = 0; i < n; i++) printf("%d", s[i]);
    printf("\n");
  }
}