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 tenPow(y):
    pass
    result = 1
    for i in range(0, y - 1):
        result *= 10
    return int(result)

s = input()

n, t = [int(i) for i in s.split()]
start = (tenPow(n))
limit = (tenPow(n + 1))

i = tenPow(n)

for i in range(start, limit):
    if i % t == 0:
        print(i)
        exit()
print(-1)