// Slower C++ solution:
#include <iostream>

#include <algorithm>

using namespace std;



int main()

{

    int N;

    pair<int, int> A[100000];

    cin >> N;

    for (int i = 0; i < N; i++)

    {

        pair<int, int> temp;

        temp.second = i;

        cin >> temp.first;

        A[i] = temp;

    }

    sort(A, A + N);

    int result = 0;

    for(int i = 0; i < N; i++)

        if(abs(A[i].second - i) % 2 != 0)

            result++;

    cout << result / 2 << endl;

    return 0;

}


// Faster C++ solution for the same problem (measured speedup: 1.7667161240405804x):
#include<bits/stdc++.h>



using namespace std;



#define    pf               printf

#define    PF(a)            printf("%d\n",(a))

#define    PF2(a,b)         printf("%d %d\n",(a), (b))

#define    PF3(a,b,c)       printf("%d %d %d\n",(a), (b), (c))

#define    PFL(a)           printf("%lld\n",(a))

#define    PFL2(a,b)        printf("%lld %lld\n",(a), (b))

#define    PFL3(a,b,c)      printf("%lld %lld %lld\n",(a), (b), (c))

#define    get(a)           cin>>a

#define    sf               scanf

#define    SF(a)            scanf("%d",&a)

#define    SF2(a,b)         scanf("%d %d",&a, &b)

#define    SF3(a,b,c)       scanf("%d %d %d",&a, &b, &c)

#define    SFL(a)           scanf("%lld",&a)

#define    SFL2(a,b)        scanf("%lld %lld",&a, &b)

#define    SFL3(a,b,c)      scanf("%lld %lld %lld",&a, &b, &c)

#define    gl(a)            getline(cin,(a))

#define    gc()             getchar()

#define    pb               push_back

#define    m_p              make_pair

#define    pc()             printf("Case %d: ",tt++)

#define    tc()             cout<<"Case "<<tt++<<": "

#define    SZ(a)            (int)(a).size()

#define    all(a)           a.begin(),a.end()

#define    FF               first

#define    SS               second

#define    MAX              2134567891

#define    MOD              1000000007

#define    MM               100005

#define    PI               2*acos(0.0)

#define    cond(n,m)        (xx>=0 && xx<(n) && yy>=0 && yy<(m))



#define    mem(a)           memset((a),0,sizeof (a))

#define    SET(a)           memset((a),-1,sizeof (a))

#define    output           freopen("output.txt","w",stdout);

#define    input            freopen("input.txt","r",stdin);

#define    I_O              ios_base::sync_with_stdio(0); cin.tie(0)

#define    rep(a)           for(int i=0;i<(a);i++)

#define    FOR(a,b)         for(int i=(a);i<(b);i++)

#define    REP(a)           for(int j=0;j<(a);j++)

#define    rev(a)           for(int i=(a);i>=0;i--)

#define    fr(i,n)          for(i=0;i<n;i++)

#define    fr1(i,n,m)       for(i=n;i<m;i++)



int dx[]  = {0, 0, 1, -1};

int dy[]  = {1, -1, 0, 0};

int dx8[] = {0, 0, 1, 1, 1, -1, -1, -1};

int dy8[] = {1, -1, -1, 0, 1, -1, 0, 1};





typedef long long ll;

typedef unsigned long long llu;

typedef priority_queue < int > PQ;

typedef pair < int, int > pi;

typedef pair < int, pi > pii;

typedef vector < int > vi;

typedef vector < ll > vl;

typedef vector < string > vs;



/*

//FUNCTION//

ll bigmod(ll a, ll b, ll c)

{

    if(b==0)return 1%c;ll x=bigmod(a,b/2,c);x=x*x%c;

    if(b%2==1)x=x*a%c;return x;

}



ll poww(ll a, ll b)

{

    if(b==0)return 1;ll x=poww(a,b/2);x=x*x;if(b%2==1)x=x*a;return x;

}



ll mod_inverse(ll a, ll mod){return bigmod(a,mod-2,mod);}



ll LCM(ll a, ll b){ return a*b/ __gcd(a,b);}



int pr = 10000000;

vi primelist;

bool a[MM*100];

void seive( )

{

    int i,j,k=sqrt(pr);

    a[1]=1;

    primelist.pb(2);

    for(i=4;i<=pr;i+=2)a[i]=1;

    for(i=3;i<=k;i+=2)if(!a[i])for(j=i*i;j<=pr;j+=2*i)a[j]=1;

    for(i=3;i<=pr;i+=2)if(!a[i])primelist.pb(i);

}



ll fact_divs( ll n, ll p)

{

    ll cnt=0;while(p<=n){cnt += n/p;n /= p;}return cnt;

}

struct point{double x, y;};

double area( point A, point B, point C){

return 0.5*(A.x*(B.y-C.y) - A.y*(B.x-C.x) + B.x*C.y - C.x*B.y);

}



//*/

ll a[MM*6];

vi odd, even;

int main() {

    I_O;

    int n;

    cin>>n;

    for(int i=1;i<=n;i++){

        cin>>a[i];

        if(i%2)odd.pb(a[i]);

        else even.pb(a[i]);

    }

    sort(odd.begin(),odd.end());

    sort(even.begin(), even.end());

    queue < int > eq, oq;

    int id = 0, idd = 0;

    ll cnt = 0;

    for(int i=1;i<=n;i++){

        if(i%2){

            while(eq.size() && eq.front()<=odd[id])eq.pop();

            cnt += (ll)eq.size()%2;

            oq.push(odd[id]);

            id++;

        }

        else {

            while(oq.size() && oq.front()<=even[idd])oq.pop();

            cnt += (ll)oq.size()%2;

            eq.push(even[idd]);

            idd++;

        }

    }

    cout<<cnt<<endl;











    return 0;

}

/*

4

2

4

3

1



8

5 1 6 2 7 3 8 4

8

1 5 2 6 3 7 4 8



*/