#include <bits/stdc++.h>
using namespace std;
#define tam 200000
#define fi first
#define pb push_back
#define se second

#define FOR(i,n)for(int j=i;j<n;j++)
typedef long long ll;
typedef pair<ll,ll> ii;
const ll INF=2e9;
int dp[tam];
const int C=4;
int main()
{

    memset(dp,-1,sizeof dp);
    dp[0]=1;
    dp[1]=1;
    for (int i = 2; i < tam; ++i)
        {
            FOR(1,i)
            {
                dp[i]=max(dp[i],dp[j]+dp[i-j]+min(j,i-j)*C);
            }
        }
   cout<<dp[tam-1]<<endl;

}