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:
class OlesyaAndRodion:
    def solve(self, n, t):
        min = (10 ** (n - 1))
        if t == 10:
            if n == 1:
                return -1
            else:
                return min
        else:
            return min * t


if __name__ == "__main__":
    n, t = map(int, raw_input().split(" "))
    oar = OlesyaAndRodion()
    print oar.solve(n, t)