#include <iostream>
#include <vector>
#include <set>
#include <queue>
#include <map>
#include <algorithm>
using namespace std;
using ll = unsigned long long;

int inf = 1e9+7;


int n;
int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    
    vector<int> stack;
    
        
    
    cin >> n;
    int s, h;
    int result = 0;
    
    for(int i = 0; i < n; i++){
        cin >> s >> h;
        
        while(!stack.empty() && stack.back() == 0)stack.pop_back();
        

        
        if(stack.empty()){
            stack.push_back(h);
        }
        else{
            if(stack.back() > h){
                while(!stack.empty() && stack.back() > h){
                    stack.pop_back();
                    result++;
                }
                if(stack.empty() || stack.back() != h) stack.push_back(h);
            
                
                
                
                
                
            }else{
                stack.push_back(h);
            }
            
        }
    }
    

    
    while(!stack.empty() && stack.back() == 0)stack.pop_back();

    
    cout << result + stack.size();

    
    
    return 0;
}


/*
 
 1 2 1 2 1 2 2 1 0 1 0 1

 10
 1 0
 2 2
 3 1
 4 2
 5 1
 6 2
 8 1
 9 0
 10 1
 11 0
 12 1
 
 1
 1 0

 */