### Background

Consider a specific set of comparable objects. Between two objects *a* and *b*, there exits one of the following three classified relations:

Because relation '=' is symmetric, it is not repeated above.

So, with 3 objects (*a*, *b*, *c*), there can exist 13 classified relations:

*
a = b = c a = b < c c < a = b a < b = c*

b = c < a a = c < b b < a = c a < b < c

a < c < b b < a < c b < c < a c < a < b

c < b < a

### Problem

Given *N*, determine the number of different classified relations between *N* objects.

### Input

Includes many integers *N* (in the range from 2 to 10), each number on one line. Ends with −1.

### Output

For each *N* of input, print the number of classified relations found, each number on one line.

### Sample