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:
import sys


def main():
    N, T = map(int, raw_input().split())
    num = []

    if(N == 1  and  T == 10):
        print -1
        sys.exit()
     
    if(T < 10):
        for i in range(N):
            num.append(T)

        print ''.join(map(str, num))


    else:
        num.append(1)
        
        for i in range(N-1):
            num.append(0)

        print ''.join(map(str, num))

        
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if(__name__ == "__main__"):
    main()