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:
n,m=map(int,input().split())
t=1
i=0
for i in range(1,n):
    t=t*10
count=0
d=m
while(d>0):
    d=d//10
    count=count+1
if(i<count-1):
    print(-1)
else:
    a=t%m
    if(a==0):
        print(t)
    else:
        c=m-a
        t=t+c
        print(t)