//By SiriusRen

#include <bits/stdc++.h>

using namespace std;

int n,xx,yy;

set<int>s1,s2;set<int>::iterator it;

long long ans;

int main(){

    scanf("%d",&n);

    for(int i=;i<=n;i++){

        scanf("%d%d",&xx,&yy);

        if(!xx){

            if(s2.empty())s1.insert(yy);

            else{

                int tmp=;

                it=s2.lower_bound(yy);

                if(it!=s2.begin())it--,tmp=min(tmp,yy-*it),it++;

                if(it!=s2.end())tmp=min(tmp,*it-yy);

                if(it!=s2.begin()){

                    it--;

                    if(yy-*it==tmp){s2.erase(it);goto ed1;}

                    it++;

                }s2.erase(it);

                ed1:ans+=tmp;

            }

        }

        else{

            if(s1.empty())s2.insert(yy);

            else{

                int tmp=;

                it=s1.lower_bound(yy);

                if(it!=s1.begin())it--,tmp=min(tmp,yy-*it),it++;

                if(it!=s1.end())tmp=min(tmp,*it-yy);

                if(it!=s1.begin()){

                    it--;

                    if(yy-*it==tmp){s1.erase(it);goto ed2;}

                    it++;

                }s1.erase(it);

                ed2:ans+=tmp;

            }

        }

    }printf("%lld\n",ans%);

}