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:
# @author Matheus Alves dos Santos
# TITLE: Olesya and Rodion
# ID: 584A

rules = map(int, raw_input().split())
number = ''

if ((rules[1] == 10) and (rules[0] == 1)):
    number = -1
    
elif (rules[1] == 10):
    number += str(rules[1])
    for i in range(rules[0] - 2):
        number += '0'

else:
    for i in range(rules[0]):
        number += str(rules[1])

print number