#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;
}