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 = list(map(int,input().split(" ")))
if n==1 and t==10:
    print("-1")
else:
    if n > 1:
        i=10**(n)
        j=i%t
        k=i-j
        if len(str(k)) < len(str(10**(n-1))):
            print("-1")
        else:
            while len(str(k)) != len(str(10**(n-1))):
                k-=t
            print(k)
    else:
        print(t)