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
n,t=map(int,sys.stdin.readline().split())
k = 10**(n-1)
ans = k/t
if ans*t == k:
    sys.stdout.write(str(k)+'\n')
elif (ans+1)*t<10*k:
    sys.stdout.write(str((ans+1)*t)+'\n')
else:
    sys.stdout.write("-1\n")