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:
import math as m
a , b= input().split()
a = int(a)
b = int(b)
if( b == 10 and a == 1 ):
    print(-1)
else:
    if(b == 10 and a == 2):
        print(10)
    else:
        mul= 1
        for x in range (0 , a - 1):
            mul *= 10
        if( b != 10):
            print(b * mul)
        else:
            print(mul)