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 = map(int, input().split())
    """if t == 2:
        print("1" * (n - 1) + "2")
    elif t == 3:
        print("3" * n)
    elif t == 4:
        if n == 1:
            print(4)
        else:
            print("1" * (n - 2) + "44")
    elif t == 5:
        print("1" * (n - 1) + "5")
    elif t == 6:
        pass
    elif t == 7:
        pass
    elif t == 8:
        if n == 1:
            print(8)
        elif n == 2:
            print(88)
        else:
            print("1" * (n - 3) + "888")
    elif t == 9:
        print("9" * n)
    elif t == 10:
        print("1" * (n - 1) + "0")"""
    if n == 1 and t == 10:
        print(-1)
        return
    if t == 10:
        print("1" * (n-1) + "0")
        return
    for i in range(1, n):
        t *= 10        
    print(t)

main()