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:
n,t = map(str,raw_input().split())
n = int(n)
t = int(t)
if n==1:
	if t==10:
		print "-1"
	else:
		print t
elif n==2:
	if t==2:
		print "10"
	if t==3:
		print "!2"
	if t==4:
		print "16"
	if t==5:
		print "10"
	if t==6:
		print "12"
	if t==7:
		print "14"
	if t==8:
		print "16"
	if t==9:
		print "18"
	if t==10:
		print "10"
else:
	num = "1"
	for i in xrange(n-2):
		num+="0"
	if t==2:
		print num+"0"
	if t==3:
		print num+"2"
	if t==4:
		print num+"4"
	if t==5:
		print num+"5"
	if t==6:
		print num+"2"
	if t==7:
		q1 = num+"0"
		q2 = num+"1"
		q3 = num+"2"
		q4 = num+"3"
		q5 = num+"4"
		q6 = num+"5"
		q7 = num+"6"
		lis = [1,3,2,6,4,5]
		su = 0
		zz= 0
		for i in range(n-1,-1,-1):
			su+=(int(q1[i])*lis[zz%6])
			zz+=1
		if su%7==0:
			print q1
		else:
			su = 0
			zz= 0
			for i in range(n-1,-1,-1):
				su+=(int(q2[i])*lis[zz%6])
				zz+=1
			if su%7==0:
				print q2
			else:
				su = 0
				zz= 0
				for i in range(n-1,-1,-1):
					su+=(int(q3[i])*lis[zz%6])
					zz+=1
				if su%7==0:
					print q3
				else:
					su = 0
					zz= 0
					for i in range(n-1,-1,-1):
						su+=(int(q4[i])*lis[zz%6])
						zz+=1
					if su%7==0:
						print q4
					else:
						su = 0
						zz= 0
						for i in range(n-1,-1,-1):
							su+=(int(q5[i])*lis[zz%6])
							zz+=1
						if su%7==0:
							print q5
						else:
							su = 0
							zz= 0
							for i in range(n-1,-1,-1):
								su+=(int(q6[i])*lis[zz%6])
								zz+=1
							if su%7==0:
								print q6
							else:
								su = 0
								zz= 0
								for i in range(n-1,-1,-1):
									su+=(int(q7[i])*lis[zz%6])
									zz+=1
								if su%7==0:
									print q7


	if t==8:
		if n==3:
			print "104"
		else:
			print num+"8"
	if t==9:
		print num+"8"
	if t==10:
		print num+"0"