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>
int main() {
  int n, t, i;
  scanf("%d %d", &n, &t);
  if (t != 10) {
    for (i = 1; i <= n; i++) printf("%d", t);
  } else {
    if (n == 1)
      printf("%d", -1);
    else {
      if (n % 2 == 0) {
        for (i = 1; i <= (n / 2); i++) printf("%d", t);
      } else {
        for (i = 1; i <= (n / 2); i++) printf("%d", t);
        printf("%d", 0);
      }
    }
  }
  return 0;
}