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:
import math

# t = int(input())
# while(t>0):

# 	t-=1
# 			
inp = input()
a = list(map(int, inp.split(" ")))
n = a[0]
t = a[1]

if(n == 1 and t == 10 ):
	print(-1)
elif(t == 10):
	print(10**(n-1))
else:
	ans= 0
	i = 0
	while(i!= n):
		ans  = ans + t*(10**(i))
		i+=1
	print(ans)