#include<bits/stdc++.h>
using namespace std;
struct student{
	int h;
	int w;
};
int main(){
	int n,cnt=0;
	cin>>n;
	student students[3005];
	for(int i=1;i<=n;i++){
		cin>>students[i].h>>students[i].w;
	}for(int j=1;j<=n-1;j++){
		for(int i=1;i<=n-j;i++){
			if(students[i].h<students[i+1].h){
				swap(students[i].h,students[i+1].h);
				swap(students[i].w,students[i+1].w);
				cnt++;
			}if(students[i].h==students[i+1].h && students[i].w<students[i+1].w){
				swap(students[i].h,students[i+1].h);
				swap(students[i].w,students[i+1].w);
				cnt++;
			}
		}
	}cout<<cnt;
	return 0;
}