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 22:11:39 2019

@author: KIIT
"""

import math
import os
import random
import re
import sys

if __name__ == '__main__':
    a = list(map(int, input().rstrip().split()))
    n,t=a[0],a[1]
    k=10**a[0]
    p=((k-1)//t)*t
    if(p>0):
        print(p)
    else:
        print("-1")