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:
# -*- coding: utf-8 -*-
"""
Created on Fri Aug 14 03:45:02 2020

@author: DELL
"""

n,t=list(map(int,input().split()))
if len(str(t))==1:
    num=str(t)*(n)
else:
    o=len(str(t))-1
    h=n-o
    num=(str(t)[0]*(h))+str(t)[1:]
if len(num)==n and  int(num)%t==0 and int(num)!=0:
    print(int(num))
else:
    print(-1)