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:
b=map(int,raw_input().split(' '))
n=b[0];k=b[1]
if k==2 or k==4 or k==8:
    if n==1:
        print 8
    if n==2:
        print 16
    if n==3:
        print 800
    if n>3:
        print '1'+(n-4)*'0'+'800'
if k==3 or k==6 or k==9:
    print n*str(k)
if k==5 or k==10:
    if k==10 and n==1:
        print -1
    if k==5 and n==1:
        print 5
    if n>1:
        print (n-1)*'1'+'0'
if k==7:
    print n*'7'