include<iostream>
using namespace std;
main(){
    int c=0,n,h[1000],w[1000],l;
    cin>>n;
    for(int a=0;a<n;a++){
        cin>>h[a]>>w[a];
    }
    for(int j=n;j>0;j--){
    for(int i=0;i<j;i++){
        if(h[i]<h[i+1]){
            l=h[i];
            h[i]=h[i+1];
            h[i+1]=l;
            l=w[i];
            w[i]=w[i+1];
            w[i+1]=l;
            c++;
        }
        else if(h[i]==h[i+1]){
            if(w[i]<w[i+1]){l=h[i];
            h[i]=h[i+1];
            h[i+1]=l;
            l=w[i];
            w[i]=w[i+1];
            w[i+1]=l;
            c++ ;}
          
        }
    }
    }
    cout<<c;
}