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#include<bits/stdc++.h>
using namespace std;

#define rep(i, n) for(int i=0;i<(int)(n);i++)
#define all(X) (X).begin(), (X).end()
#define sz(X) ((int)(X).size())
#define mp make_pair
#define st first
#define nd second
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;

int n;
int solve(vi tab) {
    int x = 2e9,res=0;
    rep(i,n) {
        if((i&1) && tab[i] <= x)
            x = 2e9, res++;
        else if(!(i&1) && tab[i] >= x)
            x = -2e9, res++;
        else x=tab[i];
    }
    return res;
}

int32_t main(){
    ios::sync_with_stdio(false);
    cin.tie(0);

    cin >> n;
    vi tab(n);
    rep(i,n) cin >> tab[i];
    int res = solve(tab);
    for(auto &a:tab) a *= -1;
    res = min(res, solve(tab));
    cout<<res<<"\n";
}