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:
def main():
    mode="filee"
    if mode=="file":f=open("test.txt","r")
    #f.readline()
    #input()
    get = lambda :[int(x) for x in (f.readline() if mode=="file" else input()).split()]
    [n,t] = get()
    if n==1 and t==10:
        print("-1")
        return
    if n==1:
        print(t)
        return
    for i in range(10**(n-1),10**(n-1) + t+1):
        if i%t == 0:
            print(i)
            return
    
        
    
    


    if mode=="file":f.close()


if __name__=="__main__":
    main()