#include <bits/stdc++.h>   using namespace std;   template <typename S, typename T>   ostream& operator<<(ostream& out, const pair<S, T> p) {     out <<  (  << p.first <<  ,  << p.second <<  ) ;     return out;   }   template <typename T>   ostream& operator<<(ostream& out, const vector<T>& v) {     for (auto a : v) out << a <<    ;     return out;   }   template <typename T>   ostream& operator<<(ostream& out, const set<T>& S) {     for (auto a : S) cout << a <<    ;     return out;   }   template <typename T>   ostream& operator<<(ostream& out, const multiset<T>& S) {     for (auto a : S) cout << a <<    ;     return out;   }   template <typename S, typename T>   ostream& operator<<(ostream& out, const map<S, T>& M) {     for (auto m : M) cout <<  (  << m.first <<  ->  << m.second <<  )  ;     return out;   }   template <typename S, typename T>   pair<S, T> operator+(pair<S, T> a, pair<S, T> b) {     return make_pair(a.first + b.first, a.second + b.second);   }   template <typename S, typename T>   pair<S, T> operator-(pair<S, T> a, pair<S, T> b) {     return make_pair(a.first - b.first, a.second - b.second);   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     int n;     cin >> n;     cout << n + n / 2 << endl;     return 0;   }   