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:
dic = {
    2: ['2', '12'],
    3: ['3', '15'],
    4: ['4', '16'],
    5: ['5', '25'],
    6: ['6', '36'],
    7: ['7', '49'],
    8: ['8', '64'],
    9: ['9', '81'],
    10: ['0', '10']
}

n, t = map(int, raw_input().split())
if n == 1 and t == 10: print -1
else:
    if n % 2:
        if t % 10 == 0: print dic[t][1] * ((n-1)/2) + dic[t][0]
        else: print dic[t][0] + dic[t][1] * ((n-1)/2)
    else:
        print dic[t][1] * (n/2)