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:
s = input().split()
n = int(s[0])
k = int(s[1])
if k == 10 :
    if (n>1):
     a1 = [1]
     a2 = [0 for i in range(n-1)]
     a = a1+a2
     print(''.join(str(i) for i in a),end='')
    else: print(-1)
else :
    for i in range(n):
        print(k,end='')