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#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int checkB(vector<int> & d, bool nextUp)
{
    int ret = 0;
    int cr = d[0];

    for(int i=1;i<d.size();i++)
    {
        if(nextUp){
            if(d[i]<=cr){
                ret+=1;
                cr = 1000000;
            }
            else cr = d[i];
            nextUp = false;
        }
        else{
            if(d[i]>=cr){
                ret+=1;
                cr = -1000000;
            }
            else cr = d[i];
            nextUp = true;
        }
    }

    return ret;
}

void B(){
    int n; cin>>n;
    vector<int> d(n,0);
    for(int i=0;i<n;i++) cin>>d[i];

    int ret = 1000000;

    int l1 = min(ret, checkB(d,true));
    int l2 = min(ret, checkB(d, false));
    reverse(d.begin(),d.end());
    int l3 = min(ret, checkB(d,true));
    int l4 = min(ret, checkB(d, false));
   // cout<<l1<<" "<<l2<<" "<<l3<<" "<<l4<<endl;
    ret = min(ret,l1);
    ret = min(ret,l2);
    ret = min(ret,l3);
    ret = min(ret,l4);

    cout<<ret<<endl;
}

int main() {
    B();
    return 0;
}