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 = map(int,input().split())
#a=map(int,raw_input().split())
#x = list(map(int, input().split()))


c = 0
num = 1


if n == 1 and t == 10:
    print("-1")
else:
    if t < 10:
        c = (n-1)
        while c !=0:
            num *= 10
            c -=1
        print(num*t)
    elif t == 10:
        c = n-2
        while c!=0:
            num *= 10
            c -=1
        print(num*t)