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:
found=1
n,k=map(int,input().split())
if(n==1):
    if(k<=9):
        print(k)
    else:
        print(-1)
    found=0
else:
    s=1
    for i in range(n-1):
        s=s*10+0
    for i in range(s+1,s+100,1):
        if(i%k==0):
            print(i)
            found=0
            break
    if(found==1):
        print(-1)