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
def sol():
    n,t=map(int,input().split())
    s=""
    if(t==10):
        if(n==1):
            s="-1"
        else:
            for i in range(n-1):
                s+=str(1)
            s+=str(0)
    else:
        for i in range(n):
            s+=str(t)
    print(s)
if(__name__=='__main__'):
    sol()
