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 Wed Oct 24 18:53:42 2018

@author: Quaint Sun
"""


n,t=map(int,input().split())

if n>1:
    if t!=10:
        print(int(''.join(['1']*n))*t)
    else:
        print(10**(n-1))
if n==1:
    for i in range(1,5):
        if len(str(i*t))==1:
            print(i*t)
            break
        else:
            print(-1)
            break