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#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<ii, ii> iii;
int MOD = 1e9 + 7;
const ld E = 1e-9;
#define null NULL
#define ms(x) memset(x, 0, sizeof(x))
#ifndef LOCAL
#define endl "\n"
#endif
#ifndef LONG_LONG_MAX
#define LONG_LONG_MAX LLONG_MAX
#endif
#define sync ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define _read(x) freopen(x, "r", stdin)
#define _write(x) freopen(x, "w", stdout)
#define files(x) _read(x ".in"); _write(x ".out")
#define filesdatsol(x) _read(x ".DAT"); _write(x ".SOL")
#define output _write("output.txt")
#define input _read("input.txt")
#define prev time_prev
#ifndef M_PI
#define M_PI acos(-1)
#endif
#define remove tipa_remove
#define next tipa_next
#define left tipa_left
#define right tipa_right
#define y1 hello_world
unsigned char ccc;
bool _minus = false;
template<typename T>
inline T sqr(T t) {
    return (t * t);
}
inline void read(ll &n) {
    n = 0;
    _minus = false;
    while (true) {
        ccc = getchar();
        if (ccc == ' ' || ccc == '\n')
            break;
        if (ccc == '-') {
            _minus = true;
            continue;
        }
        n = n * 10 + ccc - '0';
    }
    if (_minus)
        n *= -1;
}
inline bool read(int &n) {
    n = 0;
    _minus = false;
    while (true) {
        ccc = getchar();
        if (ccc == ' ' || ccc == '\n') {
            if (ccc == '\n')
                return true;
            break;
        }
        if (ccc == '-') {
            _minus = true;
            continue;
        }
        n = n * 10 + ccc - '0';
    }
    if (_minus)
        n *= -1;
    return false;
}
char wwww[19];
int kkkk;
inline void write(ll y) {
    long long x = y;
    kkkk = 0;
    if (x < 0) {
        putchar('-');
        x *= -1;
    }
    if (!x){
        ++kkkk; wwww[kkkk] = '0';
    }else
        while (x) {
            ++kkkk;
            wwww[kkkk] = char(x % 10 + '0');
            x /= 10;
        }
    for (int i = kkkk; i >= 1; --i)
        putchar(wwww[i]);
}
#ifdef LOCAL
//#define __DEBUG
#endif
#ifdef __DEBUG
#define dbg if(1)
#else
#define dbg if(0)
#endif
 
const int MAX = 1e5;
int dp[MAX][2];

void solve() {
    int n;
    cin >> n;
    vector<int> v(n);
    for (int i = 0; i < n; i++) {
        cin >> v[i];
        dp[i][0] = dp[i][1] = (int) 1e9;
    }
    dp[n][0] = dp[n][1] = (int) 1e9;
    
    dp[1][0] = dp[1][1] = 0;
    
    dp[2][0] = dp[2][1] = 1;
    if (v[0] < v[1]) {
        dp[2][1] = 0;
    } else {
        dp[2][1] = 1;
    }
    if (v[0] > v[1]) {
        dp[2][0] = 0;
    } else {
        dp[2][0] = 1;
    }
    
    for (int i = 3; i <= n; i++) {
        if (v[i - 2] < v[i - 1]) {
            dp[i][1] = dp[i - 1][0];
        }
        if (v[i - 2] > v[i - 1]) {
            dp[i][0] = dp[i - 1][1];
        }
        dp[i][0] = min(dp[i][0], dp[i - 2][0] + 1);
        dp[i][1] = min(dp[i][1], dp[i - 2][1] + 1);
    }
    cout << min(dp[n][0], dp[n][1]) << endl;
}
 
int main() {
    sync;
    srand((unsigned int) time(NULL));
    cout.precision(10);
    cout << fixed;

    
    int t = 1;
    
    while(t--){
        solve();
    }
    
}