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 = input().split()
n=int(n)
t=int(t)
e =1
i=1
if(n>=1 and n<=100 and t>=2 and t<=10):
    while(i<n):
        e=e*10
        i=i+1
    r=e*10
    while(e<r):
        if(e%t==0):
            break
        elif(e%t!=0 and e==r-1):
            break
        e=e+1
    if (e % t == 0):
        print(e)
    else:
        print("-1")