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:
import sys

def main(n, k):
    base = 10**(n - 1)
    top = 10**n
    while base < top:
        if base % k == 0:
            return base
        base += 1
    return -1

if __name__ == "__main__":
    for e, line in enumerate(sys.stdin.readlines()):
        n, k = list(map(int, line.strip().split()))

    # Proof by induction that sorting is that
    # same as solving this problem.
    print(main(n, k))