CF584A Olesya and Rodion

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 $ .

The single line contains two numbers, $ n $ and $ t $ ( $ 1

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.