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 sys
n,t = [int(x) for x in input().split()]
for i in range(1,n + 1):
	x = 10;
	if(n - i == 0):
		x = 1
	a = -1
	if(i > 1):
		a = 0
	for j in range(1,10):
		if(((j % t) * (x % t)) % t == 0):
			a = j;
	if(a == -1):
		print(-1)
		sys.exit()
	else :
		print(a,end = '')