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:
s=(input())
n,t=[int(i) for i in s.split()]
i=0
s1="1"
s1+="0"*(n-1)
s1=int(s1)
s=s1*10

while s1//s==0:
    if s1%t==0:
        i=1
        
        print(s1)
        break
    s1+=1
if i==0:
    print("-1")