from collections import deque
N = int( input())
if N == 1:
    ans = 0
else:
    ans = 0
    d = deque()
    t = N//2
    if N%2 == 0:
        for i in range(t):
            if i%2 == 0:
                d.appendleft(t-i)
                d.append(t+1+i)
            else:
                d.appendleft(t+1+i)
                d.append(t-i)
    else:
        d.append(t+1)
        for i in range(t):
            if i%2 == 0:
                d.appendleft(t-i)
                d.append(t+i+2)
            else:
                d.appendleft(t+i+2)
                d.append(t-i)
    for i in range(N):
        ans += d[i]*d[(i+1)%N]
print(ans)