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
#include <iostream>
#include <algorithm>

using namespace std;

int checkSeq(int* tab, int n, bool isFirstMin) {

    int checker = 0;
    int res = 0;

    checker += (int)isFirstMin;

    for(int i=1; i<n; i++) {
        if(i % 2 == checker) {
            if(tab[i-1] >= tab[i]) {
                tab[i] = 1e9;
                res++;
            }
        }
        else {
            if(tab[i-1] <= tab[i]) {
                tab[i] = -1e9;
                res++;
            }
        }
    }
    delete[] tab;
    return res;

}

int main() {
    ios_base::sync_with_stdio(0);

    int n;
    cin >> n;
    int* inp = new int[n];
    int *firstMax = new int[n];
    int *firstMin = new int[n];

    for(int i=0; i < n; i++) {
        cin >> inp[i];
    }
    
    copy(inp, inp + n, firstMax);
    copy(inp, inp + n, firstMin);    

    cout << min(checkSeq(firstMin, n, true), checkSeq(firstMax, n, false)) << endl;

    delete []inp;

    return 0;
}