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:
# your code goes here
import sys
n,t = map(int,sys.stdin.readline().split())
x = 1
flag = 0
n= n-1
while (n>0):
    x = x*10
    n = n - 1
#print (x + "$")
y=x*10
while (x<y):
    a=x%t;
    if (a == 0):
        print (x)
        flag = 1
        break
    x=x+1
if (flag == 0):
        print (-1)