#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define pii pair<int,int>
#define sz size()
#define all(v) v.begin(),v.end()
#define fi first
#define se second
const int N = 5e5;
const int mod = 1e9+7;
const ll INF = 1e18;
const int di[] = {1, -1, 0, 0};
const int dj[] = {0, 0, 1, -1};
ll a[N+1],b[N+1],ind[N+1];
ll pref[N+1],t[4*N];
bool cmp(int i,int j){
if(a[i]==a[j])
return b[i]<b[j];
return a[i]<a[j];
}
void upd(int v,int l,int r,int pos,ll x){
if(l==r){
t[v]=x;
}
else{
int mid=(l+r)/2;
if(pos<=mid)
upd(v+v,l,mid,pos,x);
else
upd(v+v+1,mid+1,r,pos,x);
t[v]=max(t[v+v],t[v+v+1]);
}
}
ll get(int v,int l,int r,int rl,int rr){
if(r<rl || rr<l)
return -INF;
if(rl<=l && r<=rr)
return t[v];
int mid=(l+r)/2;
return max(get(v+v,l,mid,rl,rr),get(v+v+1,mid+1,r,rl,rr));
}
void solve() {
int n;
cin>>n;
for(int i = 1; i <= n; i++){
cin>>a[i]>>b[i];
ind[i]=i;
}
sort(ind+1,ind+n+1,cmp);
for(int i = 1; i <= n; i++){
pref[i]=pref[i-1]+b[ind[i]];
upd(1,1,n,i,pref[i]-a[ind[i]]);
}
ll ans=0;
for(int i = 1; i <= n; i++){
ans=max(ans,get(1,1,n,i,n)-(pref[i-1]-a[ind[i]]));
}
cout<<ans<<"\n";
}
int main() {
//freopen("cowrun.in","r",stdin);
//freopen("cowrun.out","w",stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int t=1;
//cin>>t;
while(t--) {
solve();
}
return 0;
}
