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 k;
  int t;
  scanf("%d %d", &k, &t);
  if (t == 10) {
    if (k == 1) {
      printf("-1");
    } else {
      for (register int i = 0; i < k - 1; i++) {
        printf("1");
      }
      printf("0");
    }
  } else {
    for (register int j = 0; j < k; j++) {
      printf("%d", t);
    }
  }
}