def dist(i,j):
    if i==j:
        return 0
    else:
        return i*j-(j-i)

from itertools import permutations
N=int(input())


if N<=8:
    X=[]
    Ans=float("Inf")

    for p in permutations(range(2,N+1)):
        p=(1,)+p+(1,)

        Money=0
        for i in range(N):
            Money+=dist(p[i],p[i+1])

        if Money<Ans:
            Ans=Money
            X=[p]
        elif Money==Ans:
            X.append(p)
elif N%2==1:
    X=[1,N]
    for k in range(2,N,2):
        X+=[k,N-k]

    Ans=0
    for i in range(N):
        Ans+=dist(X[i],X[i+1])
elif N%4==0:
    X=[1,N]
    for k in range(2,N//2,2):
        X+=[k,N-k]
    X+=[N//2]
    for k in range(N//2+1,N,2):
        X+=[k,N-k]
    Ans=0
    for i in range(N):
        Ans+=dist(X[i],X[i+1])
elif N%4==2:
    X=[1,N]
    for k in range(2,N//2,2):
        X+=[k,N-k]
    X+=[N//2]
    for k in range(N//2+2,N,2):
        X+=[k,N-k]
    Ans=0
    for i in range(N):
        Ans+=dist(X[i],X[i+1])
print(Ans)