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:
#
#def mailowanie(nr_cities, city_coordinates):
#	cities = city_coordinates.split()
#	cities_inty = [int(a) for a in cities]
#	lista_wynikow = []
#	for x in cities_inty:
#		wyniki = [abs(x-a) for a in cities_inty if x-a != 0]
#		result = [min(wyniki), max(wyniki)]
#		lista_wynikow.append(result)
#	return lista_wynikow
#nr_cities = input()
#city_coordinates = input()
#eureka = mailowanie(nr_cities, city_coordinates)
#for a in eureka:
#	print(a[0],a[1])
#

#-7,-6,-5, 1, 4, 6, 7,
#
#
#
#def input_mailowanie_100k(liczba_miast):
#	alibaba = [a for a in range(int(liczba_miast))]
#	return alibaba
##liczba_miast = input()
#
#lista_miast = input_mailowanie_100k(100000)
#
#
#
#def minmax_zamiast_lambdy(lista_miast, kordy_miasta):
#	maksMin = lista_miast[0]
#	maksMax = lista_miast[-1]
#	resultMax = max(abs(maksMax - kordy_miasta), abs(maksMin - kordy_miasta))
#
#	indexMiasta = lista_miast.index(kordy_miasta)
#	
#	if indexMiasta == len(lista_miast)-1:
#		closestCity = lista_miast[indexMiasta-1]
#		lowerDistance = abs(kordy_miasta-closestCity)
#	elif indexMiasta == 0:
#		closestCity = lista_miast[1]
#		lowerDistance = abs(kordy_miasta-closestCity)
#	else:
#		resultMin1 = indexMiasta+1
#		resultMin = indexMiasta-1
#		lowerDistance = min(abs(lista_miast[resultMin1]-kordy_miasta), abs(lista_miast[resultMin]-kordy_miasta))
#
#	return abs(lowerDistance), abs(resultMax)
#
#def mailowanie(kordy_miasta, lista_miast):
#	#najmniejszNajwieksza = [minmax_zamiast_lambdy(lista_miast, a) for a in lista_miast]
#	
#	for a in lista_miast:
#		najmniejszNajwieksza = minmax_zamiast_lambdy(lista_miast, a)
#		a = najmniejszNajwieksza[0],najmniejszNajwieksza[1]
#		#print(najmniejszNajwieksza[0],najmniejszNajwieksza[1])
#	#return str(najmniejszNajwieksza)
#	return ""
#
#
#
#kordy_miasta = 10
#mailowanie(kordy_miasta,lista_miast)


#
#
#
#kordy_miasta = input()
#lista_miast = input()
#kordy_miasta = int(kordy_miasta)
#lista_miast = lista_miast.split()
#lista_miast = [int(a) for a in lista_miast]
#print(mailowanie(kordy_miasta,lista_miast))

#CHIPS

#
#def NajnizszaCenaDoKoorda(chipsNr,coordinateChip):
#	parzyste = [a for a in coordinateChip if a % 2 == 0]
#	nieParzyste = len(coordinateChip) - len(parzyste)
#	return min(len(parzyste), nieParzyste)
#	
#chipsNr = input()
#coordinateChip = input()
#chipsNr = int(chipsNr)
#coordinateChip = coordinateChip.split()
#coordinateChip = [int(a) for a in coordinateChip]
#print(NajnizszaCenaDoKoorda(chipsNr,coordinateChip))


#A. Devu, the Singer and Churu, the Joker


#if nrOfSongs -1 >= eventTime // 10 or totaTimeOfSongs + (nrOfJokes * 5) > eventTime:
#
#def schedule(n_d, timeOfSongs):
#	nrOfSongs, eventTime = n_d.split()
#	nrOfSongs = int(nrOfSongs)
#	eventTime = int(eventTime)
#	totaTimeOfSongs = sum(timeOfSongs)
#	timeForJokes = eventTime - (totaTimeOfSongs)
#	nrOfJokes = timeForJokes // 5
#	if totaTimeOfSongs + (nrOfSongs -1)*10 > eventTime:
#		return -1
#	return nrOfJokes
#
#
#n_d = input()
#timeOfSongs = input()
#timeOfSongs = timeOfSongs.split()
#timeOfSongs = [int(a) for a in timeOfSongs]
#print(schedule(n_d, timeOfSongs))


#A. Display The Number
#
#def theBiggestNr(t,n):
#	n = n.split()
#	n = [int(a) for a in n]
#	for a in n:
#		biggestNr = a//2
#		if a % 2 != 0:
#			inputOdd = "7" + (biggestNr - 1) * "1"
#			print(inputOdd)
#		else:
#			inputEven = biggestNr*"1"
#			print(inputEven)
#	return ""
#
#t = input()
#t = int(t)
#n = ""
#for i in range(t):
#    n+=input()+"\n"
#
#print(theBiggestNr(t,n))
#


#B. Make Product Equal One

#a*a*a*a...a*a*a*a = 1

#all a's shall be 1 or -1
#atleast 2*(-1)

#def equalisingProducts(nrOfNumbers,numbers):
#	counterPos = [abs(a-1) for a in numbers if a > 0 and a != 1 and a != -1]
#	counterNeg = [abs(a+1) for a in numbers if a <= 0 and a != 1 and a != -1]
#	result = sum(counterPos) + sum(counterNeg)
#	wszystkieNaMinusiePlusZero = [a for a in numbers if a <= 0]
#	if len(wszystkieNaMinusiePlusZero) % 2 != 0 and 0 not in wszystkieNaMinusiePlusZero:
#		result += 2
#	return result
#
#
#nrOfNumbers = input()
#nrOfNumbers = int(nrOfNumbers)s
#numbers = input()
#numbers = numbers.split()
#numbers = [int(a) for a in numbers]
#print(equalisingProducts(nrOfNumbers, numbers))

# pirahna's jebany probnlem
#
#
#def dominantPirahnas(numberOfTests, nrOfPirahnas, listOfpirahnas):
#	for a in listOfpirahnas:
#		allPyrahnasAreTheSame = all(rybki == a[0] for rybki in a)
#		if allPyrahnasAreTheSame:
#			print("-1")
#		else:
#			najwiekszaRybka = max(a)
#			#najwiekszaRybka = a.index(najwiekszaRybka)
#			for rybaIdx,ryba in enumerate(a):
#				
#				if ryba == najwiekszaRybka:
#					if rybaIdx == 0:
#						if a[rybaIdx + 1] < a[rybaIdx]:
#							print(rybaIdx+1)
#							break
#					elif rybaIdx == len(a) - 1:
#						if a[rybaIdx - 1] < a[rybaIdx]:
#							print(rybaIdx+1)
#							break
#					else:
#						if a[rybaIdx - 1] < a[rybaIdx] or a[rybaIdx + 1] < a[rybaIdx]:
#							print(rybaIdx+1)
#							break
#	return ""
#
#
#numberOfTests = input()
#numberOfTests = int(numberOfTests)
#nrOfPirahnas = []
#listOfpirahnas = []
#for n in range(numberOfTests):
#	nrOfPirahnas.append(input())
#	listOfpirahnas.append(input())
#listOfpirahnas = [a.split() for a in listOfpirahnas]
#listOfpirahnas = [list(map(int, a)) for a in listOfpirahnas]
#dominantPirahnas(numberOfTests, nrOfPirahnas, listOfpirahnas)

# Magic numbers
#def isItThoughaMmagicNumber(number):
#	yesAndNos = []
#	for a in number:
#		if number[0] is not "4":
#			if a is "1" or a is "4":
#				yesAndNos.append("YES")
#			else:
#				yesAndNos.append("NO")
#		else:
#			return "NO"
#	yesAndNos = yesAndNos.count("YES")
#	if "1444" in number:
#		return "NO"
#	if yesAndNos == len(number):
#		return "YES"
#	else:
#		return "NO"
#number = input()
#print(isItThoughaMmagicNumber(number))

#A. Cubes Sorting


#def canCubesSort(a):
#    if a == sorted(a, reverse = True) and len(set(a)) == len(a):
#        return "NO"
#    else:
#        return "YES"
#
#numberOfTests = input()
#numberOfTests = int(numberOfTests)
#volumesOfCubes = []
#for n in range(numberOfTests):
#	_ = input()
#	volumesOfCubes.append(input())
#volumesOfCubes = [a.split() for a in volumesOfCubes]
#volumesOfCubes = [list(map(int, a)) for a in volumesOfCubes]
#for a in volumesOfCubes:
#	print(canCubesSort(a))



#def dzielniki(liczba):
#    dzzielniki = []
#    for a in range(liczba):
#        if a == 0:
#            continue
#        elif liczba % a == 0:
#            dzzielniki.append(a) 
#    return dzzielniki
#
#
#def liczbyPierwsze(dzzielniki):
#    yesOrNo = []
#    for a in dzzielniki:
#        dzielnikiA = dzielniki(a)
#        if len(dzielnikiA)+1 <= 2:
#            return"YES"
#        else:
#            yesOrNo.append("NO")
#    if "YES" not in yesOrNo:
#       return"NO"
#
#        
#def kurwaKoniec(x):
#    roznica = x[0] - x[1]
#    return liczbyPierwsze(dzielniki(roznica))
#



# OSTATECZNE ROZWIAZANIE
#
#numberOfTests = input()
#numberOfTests = int(numberOfTests)
#nums = []
#for n in range(numberOfTests):
#    nums.append(input())
#nums = [a.split() for a in nums]
#nums = [list(map(int, a)) for a in nums]
#for x in nums:
#    roznica = x[0] - x[1]
#    if roznica>1:
#        print("YES")
#    else: 
#        print("NO")
#


#A. Subset Mex
"""
4
6
0 2 1 5 0 1
3
0 1 2
4
0 2 0 1
6
1 2 3 4 5 6


1
6
1 2 3 4 5 6 

- 0

1
6
0 2 1 5 0 1


-5
"""

#
#nums1=[0, 1, 2, 3, 5, 6, 7] 
#nums2 = []
#for a in nums1:
#    numIdx = nums1.index(a)
#    print(numIdx)
#for i in nums1:
#    numIdx = nums1.index(i)
#    print(numIdx)
#    if nums1[numIdx-1] != nums1[numIdx]-1  or i == 0:
#        #nums2.extend(nums1[numIdx+1:])
#        nums1 = nums1[:numIdx+1]
#numberOfTests = input()
#numberOfTests = int(numberOfTests)
#nums = []
#for n in range(numberOfTests):
#    _ = input()
#    nums.append(input())
#nums = [a.split() for a in nums]
#nums = [list(map(int, a)) for a in nums]
# PASTE YOUR WOFPlayer CLASS (from part A) HERE
# PASTE YOUR WOFHumanPlayer CLASS (from part B) HERE
# PASTE YOUR WOFComputerPlayer CLASS (from part C) HERE

#A. Dreamoon and Ranking Collection


#def missingNr(lista, MoreContests):
#    missingNums=[]
#    x=0
#    while len(missingNums) < MoreContests:
#        x+=1
#        if x not in lista:
#            missingNums.append(x)
#    return missingNums
#
#def finalResult(lista,listaMissing):
#    uzupelnionalista=sorted(lista+listaMissing)
#    for a in range(1,len(uzupelnionalista)+2):
#        if a not in uzupelnionalista:
#            return print(a-1)
#    return ""
#
#textCases = int(input())
#placesLst = []
#xMoreContests = []
#for n in range(textCases):
#    xMoreContests.append(input().split()[-1])
#    placesLst.append(input().split())
#placesLst = [list(map(int, a)) for a in placesLst]
#xMoreContests = [int(a) for a in xMoreContests]
#
#x=0
#for lista in placesLst:
#    finalResult(lista,missingNr(lista,xMoreContests[x]))
#    x+=1
#
#



#def digitsSum(number):
#    lst = [1,2,3,4,5,6,7,8,9]
#    string = ""
#    if number>45:
#        return -1
#    if number in lst:
#        return number
#    num=[]  
#    tempNr = number
#    for x in sorted(lst,reverse=True):
#        if tempNr < x:
#            num.append(tempNr)
#            num = [str(a) for a in num]
#            return "".join(sorted(num))
#        tempNr = tempNr-x
#        num.append(x)
#        if sum(num) == number:
#            num = [str(a) for a in num]
#            return "".join(sorted(num))
#    return -1
#
#
#
#textCases = int(input())
#tNums = []
#for n in range(textCases):
#    tNums.append(int(input()))
#
#for a in tNums:
#    print(digitsSum(a))


#Weird pedofile

#(roznica**(1/3).is_integer())





# fucking santa problem
#
#def weirdPedolife(kidsAndCandies):
#    candies,kids = kidsAndCandies[0],kidsAndCandies[1]
#    iloraz = candies/kids
#    if iloraz - int(iloraz) > 0.5:
#        return int((int(iloraz)+0.5)*kids)
#    return candies
#
#
#textCases = int(input())
#kidsAndCandies = []
#for n in range(textCases):
#    kidsAndCandies.append(input().split())
#kidsAndCandies = [list(map(int, a)) for a in kidsAndCandies]
#for a in kidsAndCandies:
#    print(weirdPedolife(a))




# sadistic coach

#def sadisticCoach(restaurants,kTime):
#    restaurants = sorted(restaurants, reverse = True)
#    for a in range(len(restaurants)):
#        joy,time = restaurants[a]
#        if time > kTime:
#            restaurants[a][0] = joy-(time-kTime)
#    return max(sorted(restaurants))[0]
#
#    
#rang,kTime = input().split()
#restaurants = []
#for a in range(int(rang)):
#    restaurants.append(input().split())
#restaurants = [list(map(int, a)) for a in restaurants]
#print(sadisticCoach(restaurants,int(kTime)))







#KOTLIN TO GOWNO
#
#def threeProblems(problemsLst,problemsNr=0):
#    problemsLstSet = list(set(problemsLst))
#    result = []
#    for a in range(len(problemsLstSet)):
#        result.append(min(problemsLstSet))
#        del problemsLstSet[problemsLstSet.index(min(problemsLstSet))]
#    if len(result)>=3:
#        for a in result[:3]:
#            result.append(problemsLst.index(a)+1)
#        return " ".join(str(x) for x in result[-3:])
#    return "-1 -1 -1"
#
#
#lenghtLst = input()
#problemsLst = []
#for a in range(1):
#    problemsLst.append((input().split()))
#problemsLst = [list(map(int, a)) for a in problemsLst]
#
#print(threeProblems(problemsLst[0]))




#theatre square
#
#import math
#def theatreSquare(lst):
#    m,n,a = lst[0],lst[1],lst[2]
#    return math.ceil(m/a)*math.ceil(n/a)
#        
#
#lst = (input().split())
#lst = [int(a) for a in lst]
##print(lst)
#print(theatreSquare(lst))


# Young Physicist
#
#def youngPhysicist(vectors):
#    x = sum([x[0] for x in vectors])
#    y = sum([x[1] for x in vectors])
#    z = sum([x[2] for x in vectors])
#
#    if x==0 and y==0 and z==0:
#        return "YES"
#    return "NO"
#
#
#nrOflines = input()
#vectors = []
#for a in range(int(nrOflines)):
#    vectors.append(input().split())
#vectors = [list(map(int, a)) for a in vectors]
##vectors = sum([sum(a) for a in vectors])
#print(youngPhysicist(vectors))


# lucky division
#def almostLuckyNum(num):
#    lst = [1,2,3,5,6,8,9]
#    check = [a for a in lst if str(a) in str(num)]
#    if check == []:
#        return "YES"
#    dzielniki = [a for a in range(1,num) if num%a==0]
#    for a in dzielniki:
#        if isThisLucky(a):
#            return "YES"
#    return "NO"
# 
#

#def isThisLucky(num):
#    false = 0
#    for a in str(num):
#        if a != "4" and a != "7":
#            false += 1
#    if false == 0:
#        return True
#    return False
#
#def almostLuckyNum(num):
#    dzielniki = [a for a in range(1,num) if num%a==0]
#    if isThisLucky(num):
#        return "YES"
#    for a in dzielniki:
#        if isThisLucky(a):
#            return "YES"
#    return "NO"
# 
#
#num=int(input())
#print(almostLuckyNum(num))


#def counting(nums):
#    a,b,c = nums
#    nums=[a+b+c,a*b*c,(a+b)*c,a*(b+c),a*b+c,a+b*c]
#    return max(nums)
#
#
#
#nums = []
#for a in range(3):
#    nums.append(int(input()))
#
#print(counting(nums))


#del a[:3]
#del b[:b.index(a[0])]
#del b[b.index(54)]
 
#while lst != sorted(lst):

#def xeniaIsAnImbecile(house,lst):
#    result = 0
#    a=0
#    while a != len(lst)-1:
#        if lst[a]>lst[a+1]:
#            del lst[:a+1]
#            result += house
#            a = 0
#            continue
#        a+=1
#    return (result-1) + max(lst)
# 
# 
# 
#house = int(input().split()[0])
#lst = input().split()
#lst = [int(a) for a in lst]
# 
#print(xeniaIsAnImbecile(house,lst))




#Fucking Pervert

#import math
#def pervert(candles,recycledCandles):
#    if candles<recycledCandles:
#        return candles
#    result=candles
#    result+=candles/recycledCandles
#    suma = []
#    c=candles/recycledCandles
#    while c/recycledCandles>=1:        
#        suma.append(c)
#        d=c/recycledCandles
#        c=d
#    suma.append(c)
#    return int(sum(suma)/recycledCandles+result)
#
#candles,recycledCandles = input().split()
#
#print(pervert(int(candles),int(recycledCandles)))



def num(nums):
    n, t = nums
    result=""
    for a in range(n-1):
        result+=str(t)[0]
    result+=str(t)[-1]
    if int(result)%t==0 and len(result)==n and result!="0":
        return result
    return -1

 
 
nums=input().split()
nums=[int(a) for a in nums]
print(num(nums))