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
def constract_number(n,t):
    if n==1 and t==10:
        print(-1)
    else:
        print(t,end='')
        if t==10:
           for i in range(n-2):
               print(0,end='')
        else:
            for i in range(n-1):
                print(0,end='')


        
def main():
    l=list()
    l=input()
    l=l.split()
    l[0]=int(l[0])
    l[1]=int(l[1])
    constract_number(l[0],l[1])






if __name__ == "__main__":
    main()