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:
m,n = map(str,input().split())
g = []
m = int(m)
if len(n)!=m and m==1:
    print('-1')
elif n=='10':
        while len(g)+1<m:
            g.append('1')
        print(''.join(g)+'0')
else:
    while len(g)<m:
        g.append(n)
    print(''.join(g))