#include<bits/stdc++.h>
#define ll long long
using namespace std;
mt19937 mt(time(NULL));
struct node{
int val,sz,add,pri;
node *l,*r;
};
node *init(int key){
node *t=new node;
*t={key,1,0,(int)mt(),0,0};
return t;
}
int sz(node *t){if(!t) return 0; return t->sz;}
void upd(node *t){if(!t) return; t->sz=sz(t->l)+sz(t->r)+1;}
void push(node *t){
if(!t) return;
if(t->add==0) return;
if(t->l) (t->l)->add+=t->add;
if(t->r) (t->r)->add+=t->add;
t->val+=t->add;
t->add=0;
}
void merge(node *&t,node *l,node *r){
if(!l) return void(t=r);
if(!r) return void(t=l);
push(l),push(r);
if(l->pri>r->pri) merge(l->r,l->r,r),t=l;
else merge(r->l,l,r->l),t=r;
upd(t);
}
void splitv(node *t,node *&l,node *&r,int k){
if(!t) return void(l=r=NULL);
push(t);
if(t->val<=k) splitv(t->r,t->r,r,k),l=t;
else splitv(t->l,l,t->l,k),r=t;
upd(t);
}
void splits(node *t,node *&l,node *&r,int k){
if(!t) return void(l=r=NULL);
push(t);
if(sz(t->l)+1<=k) splits(t->r,t->r,r,k-sz(t->l)-1),l=t;
else splits(t->l,l,t->l,k),r=t;
upd(t);
}
int fmn(node *t){
push(t);
if(t->l) return fmn(t->l);
return t->val;
}
int fmx(node *t){
push(t);
if(t->r) return fmx(t->r);
return t->val;
}
ll fsum(node *t){
ll ret=0;
if(!t) return 0;
push(t);
ret=(ll)(t->val)*(ll)(t->val);
ret+=fsum(t->l)+fsum(t->r);
return ret;
}
void deb(node *t){
push(t);
if(t->l) deb(t->l);
cout<<t->val <<" ";
if(t->r) deb(t->r);
}
int main(){
int n; cin>>n;
ll s=0;
vector<pair<int,int>> v;
for(int i=0;i<n;i++){
int h,k; cin>>h >>k;
v.push_back({h,k});
s+=(ll)k;
}
int ti=0;
sort(v.begin(),v.end());
node *t=NULL;
for(auto [h,k]:v){
while(ti<h){
ti++;
node *tmp=init(0);
merge(t,tmp,t);
}
node *l,*r;
splits(t,l,r,k);
// cout<<"hi";
// deb(l);
// cout<<"\n";
// cout<<"hello";
// deb(r);
// cout<<"\n";
l->add++;
if(r==0){
merge(t,l,r);
continue;
}
int mn=fmn(r),mx=fmx(l);
if(mx<=mn){
merge(t,l,r);
continue;
}
//cout<<"gotmn" <<mn <<"\n";
node *tl,*tr;
splitv(l,tl,tr,mn);
merge(t,tl,r);
mn=fmn(tr);
splitv(t,l,r,mn);
merge(t,l,tr);
merge(t,t,r);
// cout<<"end ";
// deb(t);
// cout<<"\n";
}
//deb(t);
//cout<<"\n";
ll sum=0;
sum=fsum(t);
cout<<(sum-s)/2LL;
}
