#include <iostream>
#include <vector>
#include <queue>
#include <map>
#include <array>
#include <set>
using namespace std;
typedef long long ll;
int v[205];
int n;
int dp[205][205][205];
int rek(int at, int dec, int inc) {
    if(at > n) {
        return 0;
    }
    if(dp[at][dec][inc] != -1) {
        return dp[at][dec][inc];
    }
    int result = 2e9;
    if((dec == 0 or v[at] < v[dec]) and (inc == 0 or v[at] > v[inc])) {
        result = min(result, rek(at + 1, at, inc));
        result = min(result, rek(at + 1, dec, at));
        result = min(result, rek(at + 1, dec, inc) + 1);
    }
    else if(dec == 0 or v[at] < v[dec]) {
        result = min(result, rek(at + 1, at, inc));
        result = min(result, rek(at + 1, dec, inc) + 1);
    }
    else if(inc == 0 or v[at] > v[inc]) {
        result = min(result, rek(at + 1, dec, at));
        result = min(result, rek(at + 1, dec, inc) + 1);
    }
    else {
        result = min(result, rek(at + 1, dec, inc) + 1);
    }
    return dp[at][dec][inc] = result;
}
int main()
{
    while(true) {
    
        cin >> n;
        if(n == -1) {
            return 0;
        }
        for(int i = 1; i <= n; i++) {
            cin >> v[i];
        }
        for(int i = 0; i < 205; i++) {
            for(int j = 0; j < 205; j++) {
                for(int k = 0; k < 205; k++) {
                    dp[i][j][k] = -1;
                }
            }
        }
        cout << rek(1, 0, 0) << endl;
    }
   
    return 0;
}