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:
#!/usr/bin/python3.4

import time

COL, ROW, LEN = 1000, 1000, 26
matrix = [[0] * COL for i in range(ROW)]
arr = [0] * LEN

direction = ((0, -1), (-1, 0), (0, 1), (1, 0))


class Pair:
    def __init__(self, x, y):
        self.x = x
        self.y = y


def timer(func, *pargs, **kargs):
    start = time.time()
    func(*pargs, **kargs)
    return time.time() - start


if __name__ == "__main__":
    n, t = map(int, input().split())
    if n == 1 and t == 10:
        print(-1)
    elif t == 10:
        print(1, "0" * (n - 1), sep="")
    else:
        print(str(t) * n)