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:
import math
n,t=map(int,input().split())
if(n==1 and t==10):
    print(-1)
elif(t!=10):
    num=1
    while(n!=0):
        num=num*10
        n-=1
    l=math.floor(math.log(num,t))
    s=t**l
    print(s)
else:
    count=1
    var=1
    while(count<n):
        var=var*10
        count+=1
    print(var)