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:
n, t = map(int, input().split())
x = 10**(n-1)
if n==1:
    if t==10:
        print(-1)
    else:
        print(t)
else:
    if t==3 or t==6 or t==9:
        print(x+8)
    elif t==1 or t==2 or t ==5 or t==10:
        print(x)
    elif t==4:
        if n==2:
            print(12)
        else:
            print(x)
    elif t==8:
        if n==2:
            print(16)
        elif n==3:
            print(104)
        else:
            print(x)
    else:
        for i in range(x, (10**n)):
            if i%t==0:
                print(i)
                break