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,t=map(int,input().split(' '))
if n==1:
    min=1
    max=10
elif n==2:
    min=10
    max=100
else:
    
    for i in range(1,n+1):
        if i==1:
            j=10
        elif i==n:
            j=j*10
            max=j
        elif i==n-1:
            j=j*10
            min=j
        else:
            j=j*10
for i in range(min,max):
    if(i%t==0):
        print(i)
        break
    elif(i==max-1):
        print(-1)