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
import math
import bisect

def solve(n, m):
    if n == 1 and m == 10:
        return -1
    a = 1
    for i in range(n - 1):
        a = a * 10
    while a % m:
        a += 1
    return a

def main():
    n, m = map(int, input().split())
    print(solve(n, m))

if __name__ == "__main__":
    main()