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:
from sys import stdin

line = stdin.read()

a, b = line.strip().split(" ")
a = int(a)
b = int(b)
#print a, b
N = pow(10, a-1)
N2 = pow(10, a)
found =  False
while(N < N2):
    if N%b == 0:
        found = True
        break
    N+=1
if found:
    print N
else:
    print -1