#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
#define pb push_back
#define pii pair<int, int>
#define pll pair<ll, ll>
#define st first
#define nd second
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define debug false
vector<pll> v;
const int MAXN = 500 * 1000;
ll maxx[MAXN * 4];
ll dodaj[MAXN * 4];
void szykuj(int i) {
dodaj[2 * i] += dodaj[i];
maxx[2 * i] += dodaj[i];
dodaj[2 * i + 1] += dodaj[i];
maxx[2 * i + 1] += dodaj[i];
dodaj[i] = 0;
}
void aktualizuj (ll x, int a, int b, int a2, int b2, int i) {
if (b < a2 || a > b2) {
return;
}
if (a <= a2 && b2 <= b) {
dodaj[i] += x;
maxx[i] += x;
return;
}
szykuj(i);
int sr = (a2 + b2)/2;
aktualizuj(x, a, b, a2, sr, i * 2);
aktualizuj(x, a, b, sr + 1, b2, i * 2 + 1);
maxx[i] = max(maxx[i * 2], maxx[i * 2 + 1]);
}
ll odczytaj (int a, int b, int a2, int b2, int i) {
if (b < a2 || a > b2) {
return (-1);
}
if (a <= a2 && b2 <= b) {
return maxx[i];
}
szykuj(i);
int sr = (a2 + b2)/2;
int akt = max(odczytaj(a, b, a2, sr, i * 2), odczytaj(a, b, sr + 1, b2, i * 2 + 1));
maxx[i] = max(maxx[i * 2], maxx[i * 2 + 1]);
return akt;
}
int main () {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n;
pll x;
cin >> n;
for (int i = 0; i < n; i ++) {
cin >> x.st >> x.nd;
v.pb(x);
}
sort(v.begin(), v.end());
ll suma = 0;
for (int i = 0; i < n; i ++) {
suma += v[i].nd;
aktualizuj(suma - (v[i].st - v[0].st), i, i, 0, n - 1, 1);
}
ll wyn = odczytaj(0, n - 1, 0, n - 1, 1);
for (int i = 1; i < n; i ++) {
aktualizuj(v[i].st - v[i - 1].st - v[i - 1].nd, i, n - 1, 0, n - 1, 1);
wyn = max(wyn, odczytaj(0, n - 1, 0, n - 1, 1));
}
cout << wyn << "\n";
return 0;
}
