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())
if n==1 and t<10:
    print(t)
elif t in [1,7]:
    print(str(t)*n)
#t=2,5,10
elif t in [2,5,10] and n>1:
    print("1"*(n-1)+"0")
#t=3,6,9
elif t in [3,6,9]:
    print("1"*(n-1)+str(t-(n-1)%t+[0,3][(n-1)%2!=0 and t==6]))
elif t in [4,8]:
    print(["16"+"0"*(n-2),"1"*(n-3)+"000"][n>3])
else:
    print(-1)