N = int(input())
sum = 0
for i in range(1,(N//3)+1,1):
    sum += 3*i-2
    sum += (3*i-1)*(3*i-1)
    sum += (3*i)*(3*i)*(3*i)
else:
    if N%3 == 0:
        pass
    elif N%3 == 1:
        sum += N
    else:
        sum += N-1
        sum += N*N
print(sum)