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:
#!/usr/bin/python

from math import *

def Nf(): return tuple(map(float, raw_input().split()))
def Ni(): return tuple(map(int, raw_input().split()))
def Nil(): return map(int, raw_input().split())
def Ns(): return raw_input().split()

n, t = Ni()
# print n, t,

if n == 1 and t == 10:
    print -1
else:
    N = "1" * (n-1) 
    n = 10 * int(N) if N != "" else 0
    r = -(n % t) + t
    print n + r