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 PYTHON):

Solution:
# coding: utf-8


def number(n, t):
    if t == 10 and n < 2:
        return -1

    if t == 10 and n > 1:
        return int("1" * (n-1) + "0")

    if t < 10:
        return int(str(t)*n)


n, t = map(int, raw_input().split())  # 1<=n<=100, 2<=t<=10

print(number(n, t))