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 = input().split()
A = int(N[0])
B = (N[1])
hasil =""
for i in range(A):
    if(B=="10"):
        if(i!=A-1):
            hasil+=B[0]
        else:
            hasil+=B[1]
    else:
        hasil+=B

if(A==1 and B=="10"):
    hasil=int(-1)
print(hasil)