#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3")
#pragma GCC optimize("O2")
#pragma GCC optimize("Ofast")
#define forn(i,n) for(int i=0;i<n;++i)
#define pb(x) push_back(x)
#define vii(a,n) vector<int>a(n);forn(i,n)cin>>a[i];
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define pi pair<int,int>
#define f first
#define s second
#define int long long
const int inf = 1e18;
const int mod = 1e9+7;//998244353;
using ll = long long;
struct sgt {
struct node {
int pref=0,suf=0,in=0,sum=0;
};
vector<node> t;
int n, sz;
node merge(node a, node b) {
node r;
r.pref = max(a.pref,a.sum+b.pref);
r.suf = max(b.suf,b.sum+a.suf);
r.sum = a.sum+b.sum;
r.in = max({a.in, b.in, a.suf+b.pref});
return r;
}
node zero;
void build(int v, int l, int r) {
if (r-l==1) return;
int m=(l+r)>>1;
build(2*v+1,l,m);
build(2*v+2,m,r);
t[v]=merge(t[2*v+1],t[2*v+2]);
}
sgt(vector<int>&a) {
n=a.size();
sz=1;
while (sz<n) sz<<=1;
t.assign(2*sz-1,zero);
forn(i,n) {
t[sz-1+i].pref=max(a[i],0ll);
t[sz-1+i].suf=max(a[i],0ll);
t[sz-1+i].sum=a[i];
t[sz-1+i].in=max(a[i],0ll);
}
build(0,0,sz);
}
node query(int v, int l, int r, int lx, int rx) {
if (r<=lx || l>=rx) return zero;
if (lx<=l && r<=rx) return t[v];
int m=(l+r)>>1;
auto L=query(2*v+1,l,m,lx,rx);
auto R=query(2*v+2,m,r,lx,rx);
return merge(L,R);
}
int query(int l, int r) {
auto ret = query(0,0,sz,l,r);
return max({ret.sum,ret.in,ret.pref,ret.suf});
}
void build(int v, int l, int r, int i) {
if (r<=i || l>i) return;
if (r-l==1) return;
int m=(l+r)>>1;
build(2*v+1,l,m,i);
build(2*v+2,m,r,i);
t[v]=merge(t[2*v+1],t[2*v+2]);
}
void set(int i, int x) {
t[sz-1+i].pref=x;
t[sz-1+i].suf=x;
t[sz-1+i].sum=x;
t[sz-1+i].in=x;
build(0,0,sz,i);
}
};
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
void solve() {
int n; cin>>n;
vector<pi> a(n);
forn(i,n) cin>>a[i].f>>a[i].s;
sort(all(a));
vector<int> b(n);
b[0]=a[0].s;
for (int i=1; i<n; ++i) {
b[i]=a[i].s-(a[i].f-a[i-1].f);
}
sgt st(b);
int ans=0;
forn(i,n) {
st.set(i,a[i].s);
ans=max(ans,st.query(i,n));
}
cout<<ans;
}
int32_t main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
int t=1;
//cin>>t;
while(t--) solve();
return 0;
}
