#include<bits/stdc++.h>
using namespace std;
int main( ){
	stack<int> music[10];
	int n,P,ANS=0;cin>>n>>P;
	while(n--){
		int i,j;cin>>i>>j;
		if(music[i].empty( )){
			ANS++;
			music[i].push(j);
		}else if(music[i].top( )<j){
			ANS++;
			music[i].push(j);
		}
		else if(music[i].top( )>j){
			while(true){
				if(music[i].top( )>j){
					music[i].pop( );
				}else if(music[i].top( )==j){
					break;
				}else if(music[i].top( )<j){
					music[i].push(j);
					ANS++;
				}
			}
		}
	}
	cout<<ANS<<endl;
	return 0;
}