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:
# Given n and t, print an int > 0 of n digits divisible by t, else return -1
# 1 <= n <= 100, 2 <= t <= 10

def answer(n, t):
    """ Returns largest n-digit number divisible by t"""
    base = int("1" + ("0" * n)) - 1
    while base % t != 0:
        base -= 1
    if base != 0:
        return base
    return -1

n, t = [int(x) for x in input().split()]
print(answer(n, t))