# include <iostream>
# include <algorithm>
using namespace std;
const int MAX=1e5+11;
int n,m=1e5;
pair<int,int> a[MAX];
struct node
{
long long sum;
int mn,pos;
node friend operator + (node A, node B)
{
node res;
res.sum=A.sum+B.sum;
if(A.mn<=B.mn)
{
res.mn=A.mn;
res.pos=A.pos;
}
else
{
res.mn=B.mn;
res.pos=B.pos;
}
return res;
}
};
node tree[MAX*4];
long long lazy[MAX*4];
void build(int v=1, int l=1, int r=m)
{
if(l==r)
{
tree[v]={0,0,l};
return ;
}
int mid=(l+r)/2;
build(v*2,l,mid);
build(v*2+1,mid+1,r);
tree[v]=tree[v*2]+tree[v*2+1];
}
void push_lazy(int v, int l, int r)
{
if(lazy[v]==0) return ;
tree[v].sum+=lazy[v]*(r-l+1);
tree[v].mn+=lazy[v];
if(l!=r)
{
lazy[v*2]+=lazy[v];
lazy[v*2+1]+=lazy[v];
}
lazy[v]=0;
}
void update(int le, int ri, int d, int v=1, int l=1, int r=m)
{
push_lazy(v,l,r);
if(ri<l or r<le) return ;
if(le<=l and r<=ri)
{
lazy[v]+=d;
push_lazy(v,l,r);
return ;
}
int mid=(l+r)/2;
update(le,ri,d,v*2,l,mid);
update(le,ri,d,v*2+1,mid+1,r);
tree[v]=tree[v*2]+tree[v*2+1];
}
node query(int le, int ri, int v=1, int l=1, int r=m)
{
push_lazy(v,l,r);
if(ri<l or r<le) return {0,(int)1e9,(int)1e9};
if(le<=l and r<=ri) return tree[v];
int mid=(l+r)/2;
return query(le,ri,v*2,l,mid)+query(le,ri,v*2+1,mid+1,r);
}
long long ans=0;
void perform(int l, int r)
{
ans+=query(l,r).sum;
update(l,r,1);
//cout<<"->"<<l<<" "<<r<<"\n";
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n;
for(int i=1;i<=n;i++) cin>>a[i].first>>a[i].second;
sort(a+1,a+n+1);
build();
for(int i=1;i<=n;i++)
{
int from=a[i].first,left=a[i].second;
node nd=query(1,from-left+1);
int pos=nd.pos;
int l=pos,r=from,pos2=pos;
while(l<=r)
{
int mid=(l+r)/2;
if(query(pos,mid).pos==pos)
{
pos2=mid;
l=mid+1;
}
else r=mid-1;
}
pos2++;
//cout<<i<<":"<<pos<<" "<<pos2<<"\n";
if(pos2<=from)
{
perform(pos2,from);
left-=from-pos2+1;
}
if(left>0)
{
perform(pos,pos+left-1);
left=0;
}
}
cout<<ans<<"\n";
return 0;
}
