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:
import math
# cook your dish here
#k=list(map(int,input().rstrip().split()))
#a=list(map(int,input().rstrip().split()))
#b=list(map(int,input().rstrip().split()))
n=list(map(int,input().rstrip().split()))
strr1='0'
t=n[1]
flag=0
for i in range (n[0]-1):
    strr1+='9'
    
#print(int(strr))

strr=strr1+'9'

num_up=int(strr)
num_low=int(strr1)

for i in range (num_low+1,num_up+1):
    if i%t==0:
        print(i)
        flag=1
        break
    
if flag==0:
    print(-1)