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#include <bits/stdc++.h>

using namespace std;

const int N = 1e5+5;
const int INF = 1e7+5;
int dp[N][2];
int a[N];

int main(){
    ios_base::sync_with_stdio(0);
    int n,res=INF;
    cin >> n;
    for(int i=1; i<=n; ++i)
        cin >> a[i];

    // dol gora dol gora
    a[0] = INF;
    for(int u=0; u<2; ++u){
        for(int i=1; i<=n; ++i){
            if(i%2==1){
                if(a[i-1] < a[i]){
                    dp[i][0] = dp[i-1][0];
                }else{
                    dp[i][0] = dp[i-1][1];
                }
                dp[i][1] = min(dp[i-1][0], dp[i-1][1])+1;
            }else{
                if(a[i-1] > a[i]){
                    dp[i][0] = dp[i-1][0];
                }else{
                    dp[i][0] = dp[i-1][1];
                }
                dp[i][1] = min(dp[i-1][0], dp[i-1][1])+1;
            }
        }
        if(u==0){
            for(int i=0; i<=n; ++i){
                a[i] *= -1;
            }
        }
        res = min(res, min(dp[n][0], dp[n][1]));
    }
    cout << res;
    return 0;
}