#include <bits/stdc++.h>
 using namespace std;
 using pii = pair<int, int>;
 using ll = long long;
 #define rep(i, j, n) for(int i = j; i < (int)(n); i++)
 const ll MOD = 1000000007;
 const ll INFL = (1LL << 60);
 const int INFI = (1 << 30);

 int main() {
   int N, K; cin >> N >> K;
   cout << N / 2.0 << endl;
 }