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 >= 2 and t <= 9): print(t)
else:
    num = int('1' + (n-1)*'0')
    cond = True
    
    if num & 1: num += 1
    
    while len(str(num)) <= n:
        if num % t == 0: 
            cond = False
            break
        else: num += 2
    
    if cond: print(-1)
    else: print(num)