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:
n, t = input().split(' ')

n = int(n)
t = int(t)

a = 10 ** (n-1)
b = 10 ** (n) 

for i in range(a, b):
    if i == b-1:
        if i%t ==0:
            print(i)
            break
        else:
            print(-1)
            break
    else:
        if i%t == 0:
            print(i)
            break

    i = i + 1