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:
def main():
    n, t = [int(t) for t in input().split()]
    low = 1
    high = (10 ** n) // t

    while low <= high:
        mid = (low + high) // 2
        digit = len(str(t * mid))
        if digit < n:
            low = mid + 1
        elif digit > n:
            high = mid - 1
        if digit == n:
            print(t * mid)
            return

    print(-1)


if __name__ == '__main__':
    main()