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())
num=1
for i in range (n-1):
    num=num*10
if(n==1 and t==10):
    num=-1
elif(t>=2 and t<=10):
    remain=num%t
    if(remain==0):
        if(t==5):
            num=num+5
        elif(t==2):
            num=num+2
        elif(t==4):
            num+=4;
        elif(t==8):
            num+=8
        else:
            num=num
    else:
        num=num-remain
        num=num+t
print num