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 n > 1:
        l = '1' + '0'*(n-1)
        l = int(l)
        u = '9' + '9'*n
        u = int(u)
    else:
        l = 1
        u = 9
    flag = False
    for i in range(l, u+1):
        if i % t == 0:
            print(i)
            flag = True
            break
    if not flag:
        print(-1)


if __name__ == '__main__':
    main()