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#include <cstdio>
#include <iostream>
#include <algorithm>
#include <string>
#include <unordered_set>
#include <queue>

using namespace std;

int t[50001];


int main(){
	int n = 0;
	cin >> n;
	for(int i = 0; i < n; ++i){
		cin >> t[i];
		//cout << t[i] << ", ";
	}
	//cout << "\n";
	int result_up = 0;
	int result_down = 0;
	bool change_up = false;
	bool change_down = false;
	int last = t[0];
	bool state = false;
	for(int i = 1; i<n; ++i){
		if(state){
			if(last < t[i]){
				//cout << "A1\n";
				if(change_up){
					change_up=false;
				}else{
					result_up++;
					change_up=true;
				}
				change_down=false;
			}else if(last > t[i]){
				//cout << "A2\n";
				if(change_down){
					change_down=false;
				}else{
					result_down++;
					change_down=true;
				}
				change_up=false;
			}else{
				//cout << "A3\n";
				if(change_up){
					change_up=false;
				}else{
					result_up++;
					change_up=true;
				}
				if(change_down){
					change_down=false;
				}else{
					result_down++;
					change_down=true;
				}
			}
		}else{
			if(last > t[i]){
				//cout << "B1\n";
				if(change_up){
					change_up=false;
				}else{
					result_up++;
					change_up=true;
				}
				change_down=false;
			}else if(last < t[i]){
				//cout << "B2\n";
				if(change_down){
					change_down=false;
				}else{
					result_down++;
					change_down=true;
				}
				change_up=false;
			}else{
				//cout << "B3\n";
				if(change_up){
					change_up=false;
				}else{
					result_up++;
					change_up=true;
				}
				if(change_down){
					change_down=false;
				}else{
					result_down++;
					change_down=true;
				}
			}
		}
		state = not state;
		last = t[i];
		//cout << " rup: " << result_up << " cup: " << change_up << " rdo: " << result_down << " cdo: " << change_down << " state: " << state << "\n";
	}
	
	if(result_up < result_down){
		cout << result_up << "\n";
	}else{
		cout << result_down << "\n";
	}
	
	return 0;
}