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#include <iostream>
#include <climits>

using std::cin, std::cout;
const char endl = '\n';
using ln = long long;

//!!! temp 50
const int MAX_N = 50'007;

int main()
{
    std::ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int n;
    cin >> n;
    
    int hievenchange = 0;
    int hioddchange = 0;

    int prevhiodd = INT_MAX;
    int prevhieven = -INT_MAX;
    for (int i = 0; i < n; i++)
    {
        int x;
        cin >> x;
        if (i%2==0)
        {
            //in hieven, x has to be higher
            //in hiodd, x has to be lower
            //than previously

            if (x > prevhieven) prevhieven = x;
            else 
            {
                hievenchange++;
                prevhieven = INT_MAX;
            }
         
            if (x < prevhiodd) prevhiodd = x;
            else 
            {
                hioddchange++;
                prevhiodd = -INT_MAX;
            }
        }
        else
        { 
            if (x > prevhiodd) prevhiodd = x;
            else 
            {
                hioddchange++;
                prevhiodd = INT_MAX;
            }
            if (x < prevhieven) prevhieven = x;
            else 
            {
                hievenchange++;
                prevhieven = -INT_MAX;
            }
        }
        //cout << prevhieven << ' ' << prevhiodd << '\n';
    }
    cout << std::min(hievenchange, hioddchange);
}