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 PYTHON3):

Solution:
def _start(n):
    s = '1'
    t = '0' * (n - 1)
    return int(s + t)

def _end(n):
    return int('9' * n)

def check(n, t):
    start = _start(n)
    end = _end(n)
    while start <= end:
        if start % t == 0:
            return start
        start += 1
    return -1

def main():
    n, t = map(int, input().split())
    print(check(n, t))
    
main()