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:
# Olesya and Rodion
def number(n, t):
    lim = t * 1
    if len(str(lim)) > n:
        return -1
    num = "1" + ("0" * (n - 1))
    i = int(num)
    while True:
        if i % t == 0:
            return i
        i += 1


n, t = list(map(int,input().rstrip().split()))
print(number(n, t))