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/python3
# -*- coding: <utf-8> -*-

import itertools as ittls
from collections import Counter
from functools import reduce

import string


def sqr(x):
    return x*x

def inputarray(func = int):
    return map(func, input().split())

# -------------------------------
# -------------------------------

n, t = inputarray()

if t == 10:
    if n == 1:
        print(-1)
    else:
        print('1' + '0'*(n - 1))
    quit()

print(str(t)*n)