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 PYTHON):

Solution:
#-------------------------------------------------------------------------------
# Name:        module1
# Purpose:
#
# Author:      wangk
#
# Created:     03/09/2017
# Copyright:   (c) wangk 2017
# Licence:     <your licence>
#-------------------------------------------------------------------------------
n,t=map(int, raw_input().split())
ans=0
if n==1:
    if t==10:
        print -1
    else:
        print t

else:
    for i in range(10**(n-1),10**(n-1)+10):
        if i%t==0:
            ans=i
            print ans
            break

    if ans==0:
        print -1