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 PYTHON):

Solution:
n,t=map(int,raw_input().split())
ans = '1' * (n - 1)
if (n == 1 and t == 10) :
    print -1
else :
    if (n == 1) :
        print t
    else : 
        c = 0
        for i in range(n - 1) :
            c = c * 10 + 1
        c *= 10
        c %= t
        ans += (chr(48 + (t - c) % t))
        print ans