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:

from random import randint

def random_with_N_digits(n):
    range_start = 10**(n-1)
    range_end = (10**n)-1
    return randint(range_start, range_end)

a=input().split()


if int(a[0])!=1:
    x=random_with_N_digits(int(a[0])-1)
    x=str(x)
    if int(a[1])%2==0:
        x=x+"0"
        while int(x)%int(a[1])!=0:
            x=random_with_N_digits(int(a[0])-1)
            x=str(x)
            x=x+"0"
    elif int(a[1])%5==0:
        x=x+"5"
        while int(x)%int(a[1])!=0:
            x=random_with_N_digits(int(a[0])-1)
            x=str(x)
            x=x+"5"
    
    else:
        x=x+"1"
        while int(x)%int(a[1])!=0:
            x=random_with_N_digits(int(a[0])-1)
            x=str(x)
            x=x+"1"
else:
    for i in range (1,10):
        if i %int(a[1])==0:
            x=i
            break
        x=-1
x=int(x)
print(x)