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:
import random
n, t = map(int, raw_input().split()) 
while (n<1 or n>100):
    n=input("Re-Enter NUM of Digits: ")
while (t<2 or t>10):
    t=input("Re-Enter NUM of division: ")
lastnum = [0,1,2,3,4,5,6,7,8,9]
oneDigit = [1,2,3,4,5,6,7,8,9]
random.shuffle(oneDigit)
random.shuffle(lastnum)
num=[]
if (n==1 and t!=10):
    for i in range(0,9):
        y=oneDigit[i]
        if (y%t==0):
            print y
            break
elif (n==1 and t==10):
    print (-1)
else:
    for x in range(0, n-1):
        if (len(num) < 1):
            num.append(random.randint(1,9))
        else:
            if( len(num) < n-1):
                num.append(random.randint(0,9))
    for i in range (0, 10):
        num.append(lastnum[i])
        b = int(''.join(map(str, num)))
        if (b%t==0):
            print b
            break
        else: num = num[:-1]