#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define ll long long
#define ld long double
#define mp make_pair
const int N=1e5+50,inf=1e9,lg=18;
const ll INF=1e18;
ll a[N+10],temp[N+10],res[N+10],pref[N+10];
struct Line{
int k;ll n;
ll operator()(ll x){return (ll)k*x+n;}
}line[N+10];
int nc,root[N+10],lc[N*lg],rc[N*lg],idx[N*lg];
void Update(int &c,int c1,int ss,int se,int i){
c=++nc;lc[c]=lc[c1],rc[c]=rc[c1],idx[c]=idx[c1];
if(!idx[c]){idx[c]=i;return;}
int mid=ss+se>>1;
if(line[idx[c]](mid)>line[i](mid))swap(idx[c],i);
if(ss==se)return;
if(line[idx[c]](ss)>=line[i](ss))Update(lc[c],lc[c1],ss,mid,i);
else Update(rc[c],rc[c1],mid+1,se,i);
}
pair<ll,int>Get(int c,int ss,int se,int x){
ll val=line[idx[c]](x);
if(ss==se)return {val,idx[c]};
int mid=ss+se>>1;
if(x<=mid){
auto [val1,i]=Get(lc[c],ss,mid,x);
if(val<val1)return {val,idx[c]};
return {val1,i};
}
else{
auto [val1,i]=Get(rc[c],mid+1,se,x);
if(val<val1)return {val,idx[c]};
return {val1,i};
}
}
int main(){
int n;scanf("%i",&n);
for(int i=1;i<=n;i++){
int h,k;scanf("%i%i",&h,&k);
temp[h-k+1]++,temp[h+1]--;
}
for(int i=1;i<=N;i++)a[i]=a[i-1]+temp[i];
for(int i=1;i<=N;i++)pref[i]=pref[i-1]+a[i];
line[0]={inf,inf};
for(int i=N;i>=1;i--){
line[i]={i,-pref[i]};
Update(root[i],root[i+1],0,N,i);
}
for(ll i=1,prefres=0;i<=N;i++){
int l=0,r=N;
while(l<=r){
int mid=l+r>>1;
int ind=Get(root[i],0,N,mid).se;
if((ind-i+1)*mid-pref[ind]+prefres>=0)res[i]=mid,r=mid-1;
else l=mid+1;
}
prefres+=res[i];
}
ll ans=0;
for(int i=1;i<=N;i++)ans+=res[i]*(res[i]-1)>>1;
printf("%lld\n",ans);
return 0;
}
