#include<bits/stdc++.h>
#define fi first
#define se second
using namespace std;
using ll = long long;
const int N = 500005;
int n;
ll ans,t[N];
pair<int,int>a[N];
ll Tinh(int l,int r,int i)
{
if(l>r) return 0;
if(l==r) return t[i]-t[l-1]-(a[i].fi-a[l].fi);
int mid=(l+r)/2;
return max(Tinh(l,mid,i),Tinh(mid+1,r,i));
}
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].fi>>a[i].se;
sort(a+1,a+n+1);
for(int i=1;i<=n;i++)
t[i]=t[i-1]+a[i].se;
for(int i=1;i<=n;i++)
ans=max(ans,Tinh(1,i,i));
cout<<ans;
return 0;
}
