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:
#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import time

#   = input()
#   = int(input())

#() = (i for i in input().split())
#   = [i for i in input().split()]

(n, t) = (int(i) for i in input().split())
#   = [int(i) for i in input().split()]

start = time.time()

min = 10**(n-1)
max = 10*min

if divmod(min, t)[1] == 0:
    ans = min
else:
    ans = min - divmod(min, t)[1] + t

if ans < max:
    print(ans)
else:
    print(-1)

finish = time.time()
#print(finish - start)