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:
# a,b = raw_input().split()
# bb=[]
# for i in range(1):
# 	bb.append(b)
# for i in range(len(bb),int(a)):
# 	bb.append('0')

# bbb=''.join(bb)

# if(len(bbb)<=int(a)):
# 	print int(bbb)
# else:
# 	print -1

a,b = map(int, raw_input().split())

if(len(str(b))>a):
	print -1
else:
	ans=b
	while(len(str(ans))<a):
		ans*=10
	print ans