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:
testa1 = "1"
a , b = map(int,raw_input().split())
testa1 += "0" * (a-1)

x = True
while True:
    if len(testa1) > a:
        break
    else:
        if int(testa1) % b == 0:
            print testa1
            x = False
            break
            
        else:
            testa1 = str(int(testa1) + 1)
if x:
    print "-1"