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=input().split(" ")
n=int(n)
t=int(t)
k=0
if n>=2:
    if t==10:
        if n>2:
            print(t**(n-1))
            k=1
        else:
            print(t)
            k=1
    else:
        for i in range(n):
            print(t,end="")
            k=1
elif n==1 and t!=10:
    print(t,end="")
    k=1
if k==0:
    print(-1)