#include <bits/stdc++.h>
#include <random>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
//#define int ll
//#define int __int128
//#define ll __int128
typedef pair<int, int   > pii;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef vector<pii> vpi;
typedef vector< vi > vvi;
typedef vector< vvi > vvvi;
typedef vector<short> vs;
typedef vector<vs> vvs;
typedef vector<vvs> vvvs;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<vvl> vvvl;
typedef vector<ld> vld;
typedef vector<vld> vvld;
typedef vector<vvld> vvvld;
typedef vector<string> vst;
typedef vector<vst> vvst;
typedef pair<ld, ld> pld;
//typedef complex<double> base;

#define inmin(a, b) a = min(a, (b))
#define inmax(a, b) a = max(a, (b))
#define ALL(a) a.begin(),a.end()
#define RALL(a) a.rbegin(),a.rend()
#define sqr(x) ((x) * (x))
#define fori(i, n) for(int i = 0; i < (int)(n); ++i)
#define SZ(a) ((int)((a).size()))
#define triple(T) tuple<T, T, T>
#define quad(T) tuple<T, T, T, T>
#define watch(x) cerr << (#x) << " = " << (x) << endl;
#define mp(a, b) make_pair(a, b)

#ifdef MAX_HOME
#define cerr cout
#else
#define cerr if (false) cerr
#endif

const double PI = 2 * acos(0.0);
#define rand shittttty_shit
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());

const string DIGITS = "0123456789";
const string ALPH = "abcdefghijklmnopqrstuvwxyz";

template <class T0, class T1>
inline ostream & operator << (ostream &out, pair<T0, T1> &a) {
    return out << "{" << a.first << ", " << a.second << "}";
}

template <class T0, class T1, class T2>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << "}";
}

template <class T0, class T1, class T2, class T3>
inline ostream & operator << (ostream &out, tuple<T0, T1, T2, T3> &a) {
    return out << "{" << get<0>(a) << ", " << get<1>(a) << ", " << get<2>(a) << ", " <<  get<3>(a) << "}";
}

template<class T>
inline ostream & operator << (ostream &out, vector<T> &a) {
    out << "[";
    fori (i, a.size())
        out << a[i] << vector<string>{", ", "]  "}[i + 1 == a.size()];
    return out;
}

ostream & operator << (ostream &out, pii a) {
    cout << a.first << " " << a.second ;
    return out;
}

void smain();

signed main() {

#ifdef MAX_HOME
    freopen("input.txt", "r", stdin);
    clock_t start = clock();
#endif
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cout << setprecision(12) << fixed;
    smain();
#ifdef MAX_HOME
    cout << "\n\n\n\nTOTAL EXECUTION TIME: " << float( clock () - start ) /  CLOCKS_PER_SEC << endl;
#endif
    return 0;
}

const int N = 1e5 + 100;

int a[N];

ll t[N << 2];

void upd(int v, int tl, int tr, int pos) {
    t[v]++;
    if (tl == tr) {
        return;
    }
    int tm = tl + tr >> 1;
    if (pos <= tm)
        upd(v << 1, tl, tm, pos);
    else
        upd(v << 1 | 1, tm + 1, tr, pos);

}

ll get(int v, int tl, int tr, int l, int r) {
    if (l > r) return 0;
    if (tl == l && tr == r)
        return t[v];
    int tm = tl + tr >> 1;
    return get(v << 1, tl, tm, l, min(tm, r)) +
           get(v << 1 | 1, tm + 1, tr, max(l, tm + 1), r);
}

void smain() {

    int cnt0 = 0, cnt1 = 1;
    int n;
    cin >> n;
    vector<int> srt;
    fori (i, n) {
        cin >> a[i];
        srt.push_back(a[i]);
    }
    sort(ALL(srt));
    int ans = 0;
    fori (i, n) {
        a[i] = lower_bound(ALL(srt), a[i]) - srt.begin();
        ans += ((a[i] & 1) ^ (i & 1));
//        cerr << "a[" << i << "] = " << a[i] << endl;
    }

    cout << ans / 2;
}

Measured memory_bytes: 1276