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,ni= (input().split())
n=int(n)
ni=int(ni)
if ni==10 and n==1:
    print(-1)
elif ni==10:
    print(10,end="")
    for i in range(0,n-2):
        print("0",end="")
    print()
elif n==1:
    print(ni)
else :
    print(ni,end="")     
    for i in range(0,n-1):
        print(0,end="")