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
def divlen(s):
	n,t = map(int, s.strip().split())
	s = str(t)

	if len(str(t)) > n:
		print '-1'
	elif n == 1:
		print t
	else:
		for i in xrange(n-2):
			s += '0'
		if(t != 10):
			s += '0'
		print s
divlen(sys.stdin.readline())