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:
'''a=[int(i) for i in input().split()]
x=a[0]
y=a[1]
z=a[2]
if y==x and z==0:
    print('0')
elif x>y+z:
    print('+')
elif y>x+z:
    print('-')
else:
    print('?')
n=int(input())
z=[int(i) for i in input().split()]
x=[]
d=0
v=''
for i in range(n):
    c=0
    e=0
    for f in range(len(z)):
        if z[f]>c and f+1 not in x:
            c=z[f]
            e=f+1
    d+=(i*c)+1
    x.append(e)
print(d)
for i in x:
    v+=str(i)
    v+=' '
print(v)

f=int(input())
g=[int(i) for i in input().split()]
for i in range(len(g)-1):
    for f in range(len(g)-1-i):
        if g[f]>g[f+1]:
            g[f],g[f+1]=g[f+1],g[f]
if g[0]*g[1]>g[-2]*g[-3] and g[-1]>0:
    print(g[-1]*g[0]*g[1])
else:
    print(g[-1]*g[-2]*g[-3])
for u in range(int(input())):
    z=int(input())
    y=[int(f) for f in input().split()]
    y.sort()
    d=0
    for i in y:
        d+=i
    if d<2048:
        print('No')
        continue
    if 2048 in y:
        print('yes')
        continue
    for x in range(z+1):
        if 2048 in y:
            print('yes')
            break
        for i in range(len(y)-1):
            if y[i]==y[i+1]:
                y[i+1]=y[i]*2
                y.pop(i)
            if i>len(y)-3:
                break
        y.sort()
    else:
        print('no')
n=int(input())
x=[]
for i in range(1,((n**2)//2)+1):
    x.append(n**2+1-i)
    x.append(i)
    if len(x)==n:
        print(*x)
        x=[]
for z in range(int(input())):
    z=int(input())
    x=[int(i) for i in input().split()]
    f=0
    o=0
    t=0
    for i in range(z):
        if x[i]%3==0:
            f+=1
        elif x[i]%3==1:
            o+=1
        else:
            t+=1
    if o<t:
        print(f+o+(t-o)//3)
    else:
        print(f+t+(o-t)//3)
n=int(input())
if n%2==1:
    print(0)
elif n%4==0:
    print((n//4)-1)
else:
    print(n//4)
n=[int(i) for i in input().split()]
if n[2]>=0 and n[0]>n[1]:
    print('NO')
elif n[2]<=0 and n[0]<n[1]:
    print('NO')
elif n[2]==0:
    if n[0]==n[1]:
        print('YES')
    else:
        print('NO')
elif (n[1]-n[0])%n[2]==0:
    print('YES')
else:
    print('NO')
for f in range(int(input())):
    f=[int(i) for i in input().split()]
    a=f[0]
    b=f[1]
    c=f[2]
    r=f[3]
    a,b=min(a,b),max(a,b)
    if c+r<=a or c-r>=b:
        print(b-a)
    elif c<=a:
        print(max(b-c-r,0))
    elif c>=b:
        print(max(c-a-r,0))
    else:
        v=max(b-c-r,0)
        print(v+max(c-a-r,0))
def bt(p,c):
    if c%p+c//p==0:
        return ''
    else:
        return bt(p,c//p)+str(c%p)
print(bt(int(input()),int(input())))
for t in range(int(input())):
    t=[int(i) for i in input().split()]
    n=t[0]
    m=t[1]
    x=t[2]
    y=t[3]
    d=0
    for f in range(n):
        e=input()
        c=0
        for i in range(m):
            if c==0 and i==m-1:
               if e[i]=='.':
                   d+=x
               break
            elif c==1:
                c=0
                continue
            else:
                if e[i]=='.' and e[i+1]=='.' and y<2*x:
                    c=1
                    d+=y
                elif e[i]=='.':
                    d+=x
                else:
                    continue
    print(d)
x=[int(i) for i in input().split()]
d=x[3]
x.pop(3)
x.sort()
a=x[0]
b=x[1]
c=x[2]
print(max(d-b+a,0)+max(d+b-c,0))
d=int(input())
s=input()
x=s.count('0')
y=s.count('1')
if y!=x:
    print(1)
    print(s)
else:
    print(2)
    print(s[0:-1],s[-1],sep=' ')
from random import choice
def qs(y):
    if len(y)<2:
        return y
    d=choice(y)
    s=[]
    e=[]
    l=[]
    for i in y:
        if i<d:
            s.append(i)
        elif i>d:
            l.append(i)
        else:
            e.append(i)
    return qs(l)+e+qs(s)
n=int(input())
m=int(input())
a=[]
d=0
for i in range(n):
    a.append(int(input()))
c=qs(a)
for i in range(n):
    d+=c[i]
    if d>=m:
        print(i+1)
        break
n=int(input())
if n%2==0:
    print((n**2)//2)
else:
    print(((n**2)//2)+1)
for f in range(n):
    c=''
    for i in range(n):
        if f%2==0:
            if i%2==0:
                c+='C'
            else:
                c+='.'
        else:
            if i%2==1:
                c+='C'
            else:
                c+='.'
    print(c)
n=int(input())
c=''
for i in range(1,n+1):
    c+=str(i)
print(c[n-1])
c=[int(i) for i in input().split()]
d=[int(i) for i in input().split()]
e=[int(i) for i in input().split()]
y=0
x=0
for i in d:
    if i%2==0:
        x+=1
for i in e:
    if i%2==0:
        y+=1
f=c[0]-x
g=c[1]-y
print(min(x,g)+min(y,f))
for i in range(int(input())):
    n=int(input())
    a=[int(i) for i in input().split()]
    a.sort()
    c=a[0]*a[-1]
    for i in range(0,4*n,2):
        if a[i]!=a[i+1]:
            print('NO')
            break
        elif a[i]*a[4*n-i-1]!=c:
            print('NO')
            break
    else:
        print('YES')
c=[int(i) for i in input().split()]
n=c[0]
m=c[1]
a=c[2]
b=c[3]
if b/m>=a:
    print(n*a)
elif (n%m)*a<b:
    print((n//m)*b+(n%m)*a)
else:
    print(((n//m)+1)*b)
a=input().split()
n=int(a[0])
l=int(a[1])
c=[int(i) for i in input().split()]
for i in range(n):
    for f in range(n-i-1):
        if c[f]>c[f+1]:
            c[f],c[f+1]=c[f+1],c[f]
d=0
for i in range(n-1):
    if (c[i+1]-c[i])/2>d:
        d=(c[i+1]-c[i])/2
if d<max(c[0],l-c[-1]):
    d=max(c[0],l-c[-1])
print(d)
d=input().split()
s=int(d[0])
n=int(d[1])
v=[]
for i in range(n):
    v.append([int(i) for i in input().split()])
for i in range(n):
    for f in range(n-i-1):
        if v[f][0]>v[f+1][0]:
            v[f],v[f+1]=v[f+1],v[f]
for i in v:
    if i[0]>=s:
        print('NO')
        break
    else:
        s+=i[1]
else:
    print('YES')
a=int(input())
c={}
for i in range(a):
    i=input()
    if i in c:
        c[i]+=1
        v=i+str(c[i])
        print(v)
    else:
        c[i]=0
        print('OK')'''
from math import sqrt
from random import randint
def ip(n):
    if n==1:
        return False
    for i in range(2,int(sqrt(n))+1):
        if n%i==0:
            return False
    return True
'''n=int(input())
v=[randint(1,n)for i in range(n)]
for i in v:
    if ip(i):
        print(i)
def s1(m,n):
    c=list(range(2,n+1))
    p=[]
    for i in range(n-1):
        if c[i]>1 and c[i]>=m:
            p.append(c[i])
            for f in range(i+1,n-1):
                if c[f]%c[i]==0:
                    c[f]=1
        elif c[i]>1:
            for f in range(i+1,n-1):
                if c[f]%c[i]==0:
                    c[f]=1
    return p'''
def s2(n):
    a=list(range(n))
    a[1]=0
    for i in a:
        if i>1:
            for j in range(i*2, len(a), i):
                a[j] = 0
    return {i**2 for i in a}
'''print(s2(1111))
def pn(n):
    c=''
    for i in range(n-1,1,-1):
        if ip(i):
            c+=str(i)
            c+=','
            break
    for i in range(n+1,100000000000000):
        if ip(i):
            c+=str(i)
            return c
print(pn(5))
v=int(input())
a=s2(v+400)
for i in range(len(a)-1):
    if a[i]<v and a[i+1]>v:
        print(a[i],a[i+1])
        break
    elif a[i]<v and a[i+1]==v:
        print(a[i],a[i+2])
        break
k=int(input())
a=s2(38000)
c=[]
for i in range(len(a)):
    if i+1 in a:
        c.append(a[i])
print(c[k-1])
c=0
a=s2(1024)
v=int(input())
d=[int(i) for i in input().split()]
d.sort()
for i in range(len(d)):
    e=0
    for j in range(len(a)):
        if d[i]%a[j]==0:
            e+=1
    if e>c:
        c=e
        v=i
print(d[v])
a=[int(i) for i in input().split()]
c=0
f=-1
for i in range(a[0],a[1]+1):
    e=0
    if ip(i):
        v=str(i)
        for j in v:
            e+=int(j)
        if e>=c:
            f=int(v)
            c=e
print(f)
a=int(input())
v=s2(1000)
for i in v:
    if a-i in v:
        c=str(i)+' '+str(a-i)
        print(c)
        break'''
'''a=int(input())
v=s2(10000)
c=0
for i in v:
    if a-i in v:
        c+=1
c//=2
if a%2==0 and a//2 in v:
    c+=1
print(c)
from math import sqrt
s=int(input())
d=[int(i) for i in input().split()]
v=s2(1000000)
for i in d:
    if i in v:
        print('YES')
    else:
        print('NO')

x=input().split()
c=int(x[0])
t=int(x[1])
e=[0]*c
for i in range(t):
    i=[int(i) for i in input().split()]
    r=0
    g=0
    for f in range(len(i)):
        if i[f]>r:
            r=i[f]
            g=f
    e[g]+=1
r=0
g=0
for f in range(len(e)):
    if e[f]>r:
        r=e[f]
        g=f
print(g+1)
x=int(input())
y=[(int(i))%2 for i in input().split()]
e=0
o=0
for i in y:
    if i==1:
        o+=1
    else:
        e+=1
print(min(e,o))
x=[int(i) for i in input().split()]
x.sort()
if x[0]==x[3]:
    if x[4]==x[5]:
        print('Elephant')
    else:
        print('Bear')
elif x[1]==x[4]:
    if x[0]==x[5]:
        print('Elephant')
    else:
        print('Bear')            
elif x[2]==x[5]:
    if x[0]==x[1]:
        print('Elephant')
    else:
        print('Bear')
else:
    print('Alien')
x=input().split()
if int(x[1])==0 and int(x[0])==0:
    print('NO')
elif int(x[1])-1==int(x[0]) or int(x[1])==int(x[0]) or int(x[1])+1==int(x[0]):
    print('YES')
else:
    print('NO')
v=input().split()
x=[]
z=int(v[0])
c=0
for i in range(z):
    x.append(input())
y=[int(i) for i in input().split()]
for i in range(int(v[1])):
    r=''
    for f in range(z):
        r+=x[f][i]
    v=max(r.count('A'),r.count('B'),r.count('C'),r.count('D'),r.count('E'))    
    c+=v*y[i]
print(c)
for i in range(int(input())):
    v=[]
    n=int(input())
    c=input()
    d=''
    if n<3:
        print('yes')
    else:
        for i in c:
            if i!=d:
                if i in v:
                    print('no')
                    break
                else:
                    v.append(i)
                    d=i
        else:
            print('yes')
for i in range(int(input())):
    d=input()
    c=int(d[0])
    for i in d:
        if int(i)<c:
            c-=1
            break
        if int(i)>c:
            break
    print((len(d)-1)*9+c)
for i in range(int(input())):
    n=int(input())
    d=[]
    e=[]
    if n==1:
        print(1)
    elif n==2:
        print(-1)
    else:
        for i in range(1,(n**2)+1,2):
            e.append(i)
            if len(e)==n:
                d.append(e)
                e=[]
        for i in range(2,(n**2)+1,2):
            e.append(i)
            if len(e)==n:
                d.append(e)
                e=[]
        for i in d:
            c=''
            for f in i:
              c+=str(f)
              c+=' '
            print(c)
for q in range( int(input()) ):  
    n = int(input())  
    v = [int(i) for i in input().split()]  
    sum_prev = 0  
    v2 = {0: 1}  
    for i in range(1, len(v)):  
        sum_prev += v[i] - v[i-1]  
        m = sum_prev - i  
        v2[m] = v2.get(m,0) + 1
    s = 0  
    for i in v2:  
        for j in range(1,v2[i]):  
            s += j  
    print(s)
for v in range(int(input()):
    v=int(input())
    d=input()
    c=d.count('*')
    if c<2 or c=v:
        print(0)
    else:
        for i in range(v):
n=int(input())
m=int(input())
if n-m!=0:
    print(round((m+n)/(n-m),1))            
else:
    print('error')
c=input()
d=''
for i in c[0:-1]:
    if i=='C':
        d+='до-'
    elif i=='D':
        d+='ре-'
    elif i=='E':
        d+='ми-'
    elif i=='F':
        d+='фа-'
    elif i=='G':
        d+='соль-'
    elif i=='A':
        d+='ля-'
    else:
        d+='си-'
i=c[-1]
if i=='C':
    d+='до'
elif i=='D':
    d+='ре'
elif i=='E':
    d+='ми'
elif i=='F':
    d+='фа'
elif i=='G':
    d+='соль'
elif i=='A':
    d+='ля'
else:
    d+='си'
print(d)
x=input().split()
y=[int(i) for i in input().split()]
m=int(x[1])
k=int(x[2])
d=0
for i in y:
    if k<0:
        break
    if i>m:
        k-=1
    else:
        d+=1
print(d)
v=input().split()
a=int(v[0])
b=int(v[1])
c=int(input())
d=b-a
if c%6==0:
    print(-1*d)
if c%6==1:
    print(a)
if c%6==2:
    print(b)
if c%6==3:
    print(d)
if c%6==4:
    print(-1*a)
if c%6==5:
    print(-1*b)
from math import sqrt
for i in range(int(input())):
    c=input()
    v=[]
    d=''
    n=0
    e=0
    for i in range(len(c)):
        d+=c[i]
        if d[-1]=='N' or d[-1]=='S' or d[-1]=='E' or d[-1]=='W':
            v.append(d)
            d=''   
    for i in v:
        if i[-1]=='N':
            n+=int(i[0:-1])
        elif i[-1]=='S':
            n-=int(i[0:-1])
        elif i[-1]=='E':
            e+=int(i[0:-1])
        else:
            e-=int(i[0:-1])
    v=str(sqrt((n**2)+(e**2)))
    x=v.find('.')
    print(v[0:x])
a=int(input())
b=int(input())
c=int(input())
print((c-a)//b)
m=int(input())
if m<3 or m==5:
    print(0)
    print(0)
elif m==4:
    print(0)
    print(1)
elif m==8:
    print(0)
    print(2)
else:
    print(4-(m%4))
    print((m-((4-(m%4))*3))//4)
m=int(input())
n=int(input())
print(((m+1)*(n+1)*m*n)//4)
v=[]
for i in range(int(input())):
    v.append(int(input()))
v.sort()
x=''
for i in v:
    x+=str(i)
    x+=' '
c=0
m=0
for i in range(1,34,4):
    d=str(i)+' '+str(i+1)+ ' '+str(i+2)+' '+str(i+3)
    if d in x and str(54-(2*(i//4))-1) in x and str(54-(2*(i//4))) in x:
        c+=1
    else:
        if c>m:
            m=c
        c=0
print(m)
x=int(input())
y=[int(i) for i in input().split()]
s=99999999999
l=0
for i in y:
    if i>l:
        l=i
    if i<s:
        s=i
v=0
d=0
if l-s>0:
    for i in y:
        if i==l:
            v+=1
        if i==s:
            d+=1
    print(l-s,d*v)
else:
    print(l-s,(x*(x-1))//2)
v=input().split()
n=int(v[0])
m=int(v[1])
if n<m:
    print(-1)
else:
    if n//2<m:
        print(m)
    else:
        if n%2==0:
            if (n//2)%m==0:
                print(n//2)
            else:
                print((n//2)+m-((n//2)%m))
        else:
            if ((n//2)+1)%m==0:
                print((n//2)+1)
            else:
                print(1+(n//2)+m-((n//2)+1)%m)
for i in range(int(input())):
    v=input().split()
    c=input().split()
    a=int(c[0])
    b=int(c[1])
    x=int(v[0])
    y=int(v[1])
    if b/2>=a:
        print((x+y)*a)
    else:
        print(b*min(x,y)+a*(max(x,y)-min(x,y)))'''
v=input().split()
n=int(v[0])
t=int(v[1])
if t==10 and n==1:
    print(-1)
elif t==10:
    print(t*(10**(n-2)))
else:
    print(t*(10**(n-1)))