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.

输入描述:

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.

输出描述:

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.