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
import math

def main():
    n, t = raw_input().split()
    n = int(n)
    t = int(t)
    
    if (n == 1 and t == 10):
        print "-1"
    else:
        x = 10 ** (n - 1)
        while True:
            if ((x % t) == 0):
                print x
                break
            x += 1
    
    
    
    return 0

if __name__ == '__main__':
    main()