/* ---------- STL Libraries ---------- */
// IO library
#include <cstdio>

#include <fstream>
#include <iomanip>
#include <ios>
#include <iostream>

// algorithm library
#include <algorithm>

#include <cmath>
#include <numeric>
#include <random>
#include <cstring>
#include <cassert>

// container library
#include <array>
#include <bitset>
#include <deque>
#include <map>
#include <unordered_map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <vector>
#include <stack>

// type
#include <cstdint>
#include <functional>

/* ---------- Namespace ---------- */
using namespace std;

/* ---------- Type ---------- */
using ll = long long;
#define int ll
template <class T> using MaxHeap = priority_queue<T>;
template <class T> using MinHeap = priority_queue<T, vector<T>, greater<T>>;
#define P pair<ll, ll>

/* ---------- Constants  */
const double PI = 3.141592653589793238462643383279;
const ll MOD = 1e9 + 7;
const int INF = 1LL << 55;

/* ---------- Functions */
template<class T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }
template<class T> bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; }

/* v-v-v-v-v-v-v-v-v Main Part v-v-v-v-v-v-v-v-v */
signed main() {
    cin.sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int N, K;
    cin >> N >> K;
    cout << 0.5 * N << endl;

    return 0;
}