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:
import sys

input = sys.stdin.readline


############ ---- Input Functions ---- ############
def inp():
    return (int(input()))


def inlt():
    return (list(map(int, input().split())))


def insr():
    s = input()
    return (list(s[:len(s) - 1]))


def invr():
    return (map(int, input().split()))

def main():
    a,b = inlt()
    if b<=9:
        print(str(b)+'0'*max(0, a-1))
    else:
        if a==1:
            print(-1)
        else:
            print(str(b) + '0' * max(0, a - 2))



if __name__ == "__main__":
    # sys.setrecursionlimit(10 ** 6)
    # threading.stack_size(10 ** 8)
    # t = threading.Thread(target=main)
    # t.start()
    # t.join()
    main()