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,t=map(int,input().split())
maxi="9"*n
if n==1:
    mini=1
else:
    mini="9"*(n-1)
    mini=int(mini)
    mini+=1
maxi=int(maxi)
#print(mini,maxi)
flag=1
for i in range(mini,maxi+1):
    if i%t==0:
        ans=i
        flag=0
        break
if flag==1:
    print("-1")
else:
    print(ans)