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