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:
# URL: http://codeforces.com/problemset/problem/584/A
# ~ Basic Implementation Problem

from typing import List


def parse_input() -> List[int]:
    return [int(x) for x in input().split()]


def solve(n: int, t: int) -> int:
    if n == 1 and t == 10:
        return -1
    elif t == 10:
        return 10 ** (n - 1)
    else:
        return int(str(t) * n)


if __name__ == '__main__':
    n, t = parse_input()
    print(solve(n, t))