#include<iostream>
#include<vector>
#include<queue>
#include<stack>
#include<algorithm>
#include<limits.h>
#include<math.h>
#include<map>
#include<set>
#include<unordered_map>
#include<unordered_set>
#include<iomanip>
#include<cstring>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using namespace std;
//const int MOD=1e9+7;
//typedef pair<ll,ll>Point;
//typedef pair<ll,ll>Line;
//#define x first
//#define y second
const int TREE_SIZE=1<<17;
ll tree[2*TREE_SIZE];
ll lazy[2*TREE_SIZE];
int beg=TREE_SIZE;
void push(int node){
if(lazy[node]){
tree[node]+=lazy[node];
if(node<TREE_SIZE){
lazy[2*node]+=lazy[node];
lazy[2*node+1]+=lazy[node];
}
lazy[node]=0;
}
}
ll get_sum(int node,int l,int r,int rl,int rr){
push(node);
if(r<=rl||rr<=l)
return 0;
if(l<=rl&&rr<=r)
return tree[node];
int m=(rl+rr)/2;
return get_sum(2*node,l,r,rl,m)+get_sum(2*node+1,l,r,m,rr);
}
ll get_sum(int l,int r){
return get_sum(1,l,r,0,TREE_SIZE);
}
void update(int node,int l,int r,int rl,int rr,int v){
push(node);
if(r<=rl||rr<=l)
return;
if(l<=rl&&rr<=r){
lazy[node]+=v;
push(node);
return;
}
int m=(rl+rr)/2;
update(2*node,l,r,rl,m,v);
update(2*node+1,l,r,m,rr,v);
tree[node]=tree[2*node]+tree[2*node+1];
}
void update(int l,int r,int v){
update(1,l,r,0,TREE_SIZE,v);
}
int get_first(int v){
int l=beg-1,r=TREE_SIZE;
while(l<r-1){
int m=(l+r)/2;
if(get_sum(m,m+1)<v)
l=m;
else
r=m;
}
return r;
}
int get_last(int v){ // get one after last
int l=beg-1,r=TREE_SIZE;
while(l<r-1){
int m=(l+r)/2;
if(get_sum(m,m+1)<=v)
l=m;
else
r=m;
}
return r;
}
void add(){
beg--;
}
ll get(int k){
if(k==0)
return 0;
int mv=(int)get_sum(beg+k-1,beg+k);
int i1=get_first(mv);
ll res=get_sum(beg,i1);
update(beg,i1,1);
k-=i1-beg;
int i2=get_last(mv);
res+=get_sum(i2-k,i2);
update(i2-k,i2,1);
return res;
}
void solve(){
int n;
cin>>n;
vector<pair<int,int>>arr(n);
for(auto&i:arr)
cin>>i.first>>i.second;
sort(arr.begin(),arr.end());
int ph=0;
multiset<int>s;
ll r=0;
for(auto [h,k]:arr){
for(int i=ph;i<h;i++)
add();
r+=get(k);
ph=h;
}
cout<<r<<"\n";
}
int main(){
ios::sync_with_stdio(false);cout.tie(NULL);cin.tie(NULL);
//freopen("bank.in","r",stdin);freopen("bank.out","w",stdout);
int t=1;//cin>>t;
while(t--)solve();
return 0;
}
/*
6
3 2
5 3
4 1
2 1
4 3
3 2
10
*/
