//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
using ll = long long;
#define pp pair<int,int>
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define ld long double
#define al(a) (a).begin(),(a).end()
#define mk make_pair
#define check cout<<"?"<<endl;

ll MOD=1000000007;
ll mod=998244353;
int inf=1000001000;
ll INF=1e18+5;

template<typename T>
ostream& operator<<(ostream& os,const vector<T>& v){
    if(v.empty()){
        os<<"{ }";
        return os;
    }
    os<<"{"<<v.front();
    for(auto itr=++v.begin();itr!=v.end();itr++){
        os<<", "<<*itr;
    }
    os<<"}";
    return os;
}

template<typename T_first,typename T_second>
ostream& operator<<(ostream& os,const pair<T_first,T_second>& P){
    os<<"("<<P.first;
    os<<", "<<P.second;
    os<<")";
    return os;
}

int main(){
    int n,k; cin>>n>>k;
    cout<<n/2.0<<endl;
}