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 PYTHON):

Solution:
# -*- coding:utf-8 -*-
import sys
def some_func():
    """
    """

    n,m = map(int, raw_input().split(' '))
    if m!=10:
        print int('1'*n)*m
    else:
        if n==1:
            print -1
        else:
            print '1'+'0'*(n-1)


if __name__ == '__main__':
    some_func()