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 Tue Jan 22 11:13:20 2019

@author: nishantwrp
"""
n,t = map(int,input().split())
if n==1 and t==10:
    print(-1)
else:
    ans = 0;
    for _ in range(n):
        ans = ((ans*10) + 9)%t
    for _ in range(n-1):
        print(9,end="")
    print(9-ans,end="")