#!/bin/python3

import sys

def cumsum(k):
    return (k*(k+1))//2
    

def sumOfGroup(k):
    # Return the sum of the elements of the k'th group.
    
    ll=k-1
    uu=k
    
    l=cumsum(ll)
    #print(l)
    u=cumsum(uu)
    #print(u)
    
    
    
    l=l*l
    u=u*u
    
    return (u -l)

if __name__ == "__main__":
    k = int(input().strip())
    answer = sumOfGroup(k)
    print(answer)