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 PYTHON):

Solution:
a = 7
n,t = raw_input().split()
n = int(n)
t = int(t)
if(n==1):
    if t == 10:
        a = -1
        print a
    else :
        a = t
        print a
else:
    for i in range(n-1):
        a = a*10
    if t in (2,3,6):
        a = a+ 8
        print a
    elif t in (7,10,5):
        print a
    elif t == 9:
        a = a+2
        print a
    elif  t==4:
        if n==2:
            a = a+2
            print a
        else :print a
    else :
        if n == 2:
            a = a + 2
            print a
        elif n == 3:
            a = a+4
            print a
        else :print a