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:
n,m=input().split(' ')
n=int(n)
m=int(m)
q=n
l=[]
l1=[]
l.append(1)
l1.append(9)
n-=1
n1=0
flag=0
while(n>0):
    l.append(0)
    l1.append(9)
    n=n-1
for i in range(0,len(l)):
    n=n*10+l[i]
    n1=n1*10+l1[i]
for i in range(n,n1+1):
    if(i%m==0):
        flag+=1
        print(i)
        break
if(flag==0):
    print(-1)