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:
import sys

lst = map(int, sys.stdin.readline().split())
res = [str(lst[1])]

if (lst[1] == 10 and lst[0] < 2):
    print -1
else:
    if lst[1] == 10:
        lst[0]-=1;

    for i in range(0, lst[0]-1):
        res.append('0');

    print ''.join(res)