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 PYTHON):

Solution:
num, div = raw_input().split()
num = int(num)

if div != "10":
    numero = int(div*num)

    div = int(div)

    if numero%div == 0:
        print numero
    else:
        print -1
else:
    numero = int("1"*(num-1)+ "0")
    div = int(div)
    if numero < div: print -1
    else:
        if numero%div == 0: print numero
        else: print -1