#include <bits/stdc++.h>
#if __has_include(<atcoder/all>)
    #include <atcoder/all>
    using namespace atcoder;
#endif

using namespace std;
using Graph = vector<vector<int>>;
using vst= vector<string>;
using vin= vector<int>;
using ll=long long;
using ull=unsigned long long;
using vll= vector<ll>;
using P=pair<int ,int>;
using pqi=priority_queue<int, vector<int>, greater<int>>;
using pqp=priority_queue<P, vector<P>, greater<P>>;

//const long double pi=acos(-1);
#define ft first
#define sd second
#define fn front
#define pb push_back
#define eb emplace_back
#define it insert
#define vvi vector<vector<int>>
#define si(v) int((v).size())
#define pq priority_queue
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rell(i,n) for (ll i=0; i< (ll)(n); i++)
#define sot(x) sort(x.begin(), x.end())
#define rese(x) reverse(x.begin(), x.end())
#define gsot(x) sort(x.begin(), x.end(), greater<ll>());
#define vnn(x,y,s,name) vector<vector<int>> name(x, vector<int>(y,s))
#define mse(x) memset(x, 0, sizeof(x))
#define all(x) (x).begin(),(x).end()
#define mii(x,y,z) min(x,min(y,z))
#define maa(x,y,z) max(x,max(y,z))
#define cps CLOCKS_PER_SEC
#define yes cout<<"Yes"<<"\n"
#define no cout<<"No"<<"\n"
#define cset(x) cout<<fixed<<setprecision(x)


//const int INF=1001001001;
//const ll INF=1e18;
//998244353  1000000007


int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    ll n;
    cin>>n;
    n/=2;
    n*=6;
    cout<<n<<endl;
}