#pragma GCC optimize("O2") #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define whlie while #define mp make_pair #define pb push_back #define eb emplace_back #define fi first #define se second #define inf 1001001001 #define infLL ( (1LL << 61)) #define MOD 1000000007 #define FOR(i,a,b) for(int (i)=((int)a); (i)<((int)b); (i)++) // [a,b) #define rep(i,N) FOR((i), 0, ((int)N)) // [0,N) #define FORR(i,a,b) for(int (i)=((int)b) - 1; (i)>=((int)a); (i)--) #define repr(i,N) FORR((i), 0, ((int)N)) #define all(v) (v).begin(),(v).end() #define rall(v) (v).rbegin(),(v).rend() #define sz(v) ((int)(v).size()) #define vrep(v,it) for(auto it=v.begin();it!=v.end();it++) #define vrepr(v,it) for(auto it=v.rbegin();it!=v.rend();it++) #define inx(t,...) t __VA_ARGS__; in(__VA_ARGS__) #define ini(...) int __VA_ARGS__; in(__VA_ARGS__) #define inl(...) ll __VA_ARGS__; in(__VA_ARGS__) #define inc(...) char __VA_ARGS__; in(__VA_ARGS__) #define ins(...) string __VA_ARGS__; in(__VA_ARGS__) #define ind(...) double __VA_ARGS__; in(__VA_ARGS__) #define inpii(...) pii __VA_ARGS__; in(__VA_ARGS__) #define invi(v,...) vi v; in(v,##__VA_ARGS__) #define invl(v,...) vl v; in(v,##__VA_ARGS__) #define mem(ar,val) memset((ar), (val), sizeof(ar) ) #define mem0(ar) memset((ar), 0, sizeof(ar) ) #define mem1(ar) memset((ar), -1, sizeof(ar) ) #ifdef LOCAL #define dbg(...) fprintf(stderr, __VA_ARGS__) #define trc(...) do { cout << #__VA_ARGS__ << " = "; dbg_out(__VA_ARGS__);} while(0) #define stopif(val) assert( !(val) ) #define vdbg(v,...) do { cout << #v << " = "; vector_debug(v , ##__VA_ARGS__);} while(0) #else #define dbg(...) 1 #define trc(...) 1 #define stopif(...) 1 #define vdbg(...) 1 #endif using namespace std; typedef long long ll; typedef pair pii; typedef pair pll; typedef vector vi; typedef vector vl; typedef vector vs; typedef vector vpii; typedef vector< vector > vvi; struct IoSetup { IoSetup() { cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(15); cerr << fixed << setprecision(15); } } iosetup; int gcd(int a, int b){if(a>b) swap(a,b); return a==0 ? b : gcd(b%a,a);} ll gcd(ll a, ll b){if(a>b) swap(a,b); return a==0 ? b : gcd(b%a,a);} int lcm(int a, int b){return (a / gcd(a,b)) * b;} ll lcm(ll a, ll b){return (a / gcd(a,b)) * b;} inline ll pow(int a, int b){ll ans = 1; rep(i,b) ans *= a; return ans;} inline ll pow(ll a, ll b){ll ans = 1; rep(i,b) ans*= a; return ans;} inline ll pow(int a, ll b){ll ans = 1; rep(i,b) ans *= a; return ans;} inline ll pow(ll a, int b){ll ans = 1; rep(i,b) ans*= a; return ans;} template inline bool amin(T &x, U y) { return (y < x) ? (x = y, true) : false; } template inline bool amax(T &x, U y) { return (x < y) ? (x = y, true) : false; } template inline void _cin(C &c){cin >> c;} template inline void _cin(pair &p){cin >> p.fi; cin >> p.se;} template inline void _cout(const C &c){cout << c;} template inline void _cout(const pair &p){cout << p.fi << ' ' << p.se;} void in(){} template void in(T &t,U &...u){ _cin(t); in(u...);} void out(){cout << "\n";} template void out(const T &t,U ...u){ _cout(t); if(sizeof...(u)) cout << ' '; out(u...);} template inline void in(vector &v,int N=-1){if(sz(v) != 0){int M=(N == -1) ? sz(v) : N; rep(i,M) _cin(v[i]);}else{C c;rep(i,N) v.pb((_cin(c),c));}} template inline void in(C v[],int N){rep(i,N) _cin(v[i]);} template inline void out(const vector &v,int N=-1){int M=(N == -1) ? sz(v) : N; rep(i,M) {cout<<( (i)?" ":"" ); _cout(v[i]);} cout<<"\n";} template inline void out(C v[],int N){rep(i,N) {cout<<( (i)?" ":"" ); _cout(v[i]);} cout<<"\n";} template inline void vector_debug(const vector &v,int N=-1){cout << "{"; int M=(N == -1) ? sz(v) : N; rep(i,M) {cout<<( (i)?", ":"" ); _cout(v[i]);} cout<<"}"< inline void vector_debug(C v[], int N){cout << "{"; rep(i,N) {cout<<((i)?", ":""); _cout(*(v+i));} cout<<"}"< void dbg_out(const T &t,U ...u){ _cout(t); if(sizeof...(u)) cout << ", "; dbg_out(u...);} template void dbg_out(const vector &v,U ...u){vector_debug(v); if(sizeof...(u)) cout << ", "; dbg_out(u...);} template void dbg_out(const vector> &v,U ...u){cout << "{ "; rep(i,sz(v)) {if(i)cout<<", "; vector_debug(v[i]);} cout << " }"; if(sizeof...(u)) cout << ", "; dbg_out(u...);} template inline C vmax(const vector &v){C n=v[0]; rep(i,sz(v)) amax(n,v[i]); return n;} template inline C vmax(C v[], int N){C n=v[0]; rep( i , N ) amax(n,v[i]); return n;} template inline C vmin(const vector &v){C n=v[0]; rep(i,sz(v)) amin(n,v[i]); return n;} template inline C vmin(C v[], int N){C n=v[0]; rep( i , N ) amin(n,v[i]); return n;} template inline C vsum(const vector &v){C n=0; rep(i,sz(v)) n+=v[i]; return n;} template inline C vsum(C v[], int N){C n=0; rep( i , N ) n+=v[i]; return n;} //////////// /// main /// //////////// int main(){ inl(N); out(N*3/2); }