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
48
49
50
51
52
53
54
55
56
57
58
59
#include <bits/stdc++.h>
using namespace std;

int main(){
    int n;
    cin >> n;

    vector <int> V(n);
    for(auto &x: V){
        cin >> x;
    }

    int ans = 0;
    bool prev = false;

    for(int i = 1; i<n; ++i){
        bool act = false;

        if(i%2 == 1){
            if(V[i] >= V[i-1] && !prev){
                ans++;
                act = true;
            }
        }else{
            if(V[i] <= V[i-1] && !prev){
                ans++;
                act = true;
            }
        }

        prev = act;
    }

    for(auto &x: V) x *= -1;

    int ans2 = 0;
    prev = false;

    for(int i = 1; i<n; ++i){
        bool act = false;

        if(i%2 == 1){
            if(V[i] >= V[i-1] && !prev){
                ans2++;
                act = true;
            }
        }else{
            if(V[i] <= V[i-1] && !prev){
                ans2++;
                act = true;
            }
        }

        prev = act;
    }


    cout << min(ans, ans2) << "\n";
}