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:
a,b=input().split()
if int(b)<=9:
    print(int(a)*str(b))
else:
    if int(b)==10 and int(a)>=2:
        print(1*'1' + (int(a)-1)*'0')
    else:
        i=1
        b=int(b)
        x=b*i
        if int(a)>=(len(str(x))):
            while (len(str(x)))!=int(a):
                i=i+1
                x=b*i
            print(x)
        else:
            print(-1)