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:
#	Author	: debugster
#	Email	: alive.dew@gmail.com
#	Date	: 2020-06-03 00:56:58

import sys
import os

def get_int():
    return map(int, input().split())

def get_array():
    return list(map(int, input().split()))

if os.environ.get("DEBUGSTER_PYTHON"):
    sys.stdin = open('in.txt', 'r')
    sys.stdout = open('out.txt','w')

n, t = get_int()
if n == 1 and t == 10:
    print(-1)
else:
    if t < 10:
        for _ in range(n):
            print(t, end = "")
    else:
        print(1, end = "")
        for _ in range(n - 1):
            print(0, end = "")