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:
def oar():
    n = input().split()
    k = int(n[0])
    j = int(n[1])
    m = 10**k - 1
    c = e = f = 1
    d = str()
    if k == 1 and j > 9:
        print('-1')
    else:    
        if j == 10:
            for i in range(k-1):
                d += str('1')
            print(d+'0')
        else:
            for i in range(k):
                d += str(j)
            print(d)
            
oar()