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 = map(int,raw_input().split())
strr = ""
str_dez = "1"
if num[0] == 1 and num[1] == 10:
    print "-1"
elif num[1] < 10:
    for i in range(num[0]):
        strr += str(num[1])
    print strr
else:
    if num[1] == 10:
        for k in range(1,num[0]):
            str_dez += "0"
        print str_dez