1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
#include<bits/stdc++.h>
using namespace std;
const int MAXN=5e4+5;
int t1[MAXN],t2[MAXN];
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n;
    cin>>n;
    for(int i=0;i<n;i++){
        cin>>t1[i];
        t2[i]=t1[i];
    }
    int w1=0,w2=0;
    for(int i=1;i<n;i++){
        if(i%2==1){
            if(t1[i]>=t1[i-1]){
                w1++;
                t1[i]=(-1*3e6);
                //cout<<'a';
            }
        }else{
           if(t1[i]<=t1[i-1]){
                w1++;
                t1[i]=3e6;
                //cout<<'b';
            }
        }
    }
    for(int i=1;i<n;i++){
        if(i%2==1){
            if(t2[i]<=t2[i-1]){
                w2++;
                t2[i]=3e6;
                //cout<<'c';
            }
        }else{
           if(t2[i]>=t2[i-1]){
                w2++;
                t2[i]=-1*3e6;
                //cout<<'d';
            }
        }
    }
    //cout<<w1<<" "<<w2;
    cout<<min(w1,w2);
}