#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define fs first
#define sc second
using namespace std;
typedef pair<ll,ll> LL;
const ll N = 5e5 + 9;
const ll inf = 1e9 + 7;
ll n,st[4*N],lazy[4*N];
LL a[N];
void Pass(ll id){
ll t = lazy[id]; lazy[id] = 0;
st[id*2] += t; lazy[id*2] += t;
st[id*2 + 1] += t; lazy[id*2 + 1] += t;
}
void upd(ll id,ll l,ll r,ll u,ll v,ll val){
if (v < l||r < u) return;
if (u <= l&&r <= v){
st[id] += val; lazy[id] += val; return;
}
ll mid = (l + r)/2; Pass(id);
upd(id*2,l,mid,u,v,val); upd(id*2 + 1,mid + 1,r,u,v,val);
st[id] = max(st[id*2],st[id*2 + 1]);
}
ll Get(ll id,ll l,ll r,ll u,ll v){
if (v < l||r < u) return 0;
if (u <= l&&r <= v) return st[id];
ll mid = (l + r)/2; Pass(id);
return max(Get(id*2,l,mid,u,v),Get(id*2 + 1,mid + 1,r,u,v));
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
#define task "tst"
if (fopen(task".INP","r")){
freopen(task".INP","r",stdin);
//freopen(task".OUT","w",stdout);
}
cin>>n;
for (ll i = 1;i <= n;i++) cin>>a[i].fs>>a[i].sc;
sort(a + 1,a + n + 1);
ll cur = 0,ans = 0;
for (ll i = 1;i <= n;i++){
cur += a[i].sc;
upd(1,1,n,i,i,cur - a[i].fs + a[1].fs);
}
ans = max(ans,Get(1,1,n,1,n)); //cout<<ans; return 0;
for (ll i = 2;i <= n;i++){
upd(1,1,n,i,n,a[i].fs - a[i - 1].fs - a[i - 1].sc);
ans = max(ans,Get(1,1,n,i,n)); //cout<<Get(1,1,n,i,n)<<"x\n";
}
cout<<ans;
}
