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)
n1=n
s=1
out=""
if n>=len(t):
    while n>0:
        out+=t
        n-=len(t)
    if n!=0:
        out=out[:n]
        if int(out)%int(t)!=0:
            ou=int(out)-(int(out)%int(t))
            print(ou)
    else:
        print(out)
else:
    print("-1")