#include <bits/stdc++.h>
#include <iostream>
#include <cmath>
#include <iomanip>
#include <vector>
#include <map>
#include <stack>
#include <queue>
using namespace std;
#define ll long long
#define pb push_back
#define el '\n'
#define mpair make_pair
#define MASK(i) (1LL << (i))
#define BIT(mask, i) (((mask) >> (i)) & 1)
#define fi first
#define se second
/* Author: Pham Gia Phuoc */
const ll MOD = (ll)(1e9) + 1LL * 19972207;
template <class T1, class T2>
void add(T1 &a, T2 b){
a += b;
if(a >= MOD) a -= MOD;
}
template <class T1, class T2>
void sub(T1 &a, T2 b){
a -= b;
if(a < 0) a += MOD;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if(a > b){a = b; return true;} return false;
}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if(a < b){a = b; return true;} return false;
}
/** END OF TEMPLATE. DRINK A CUP OF COFFEE BEFORE READING MY CODE **/
const int MAX = 500010;
const ll INF = (ll) 1e18 + 67LL;
const int oo = (int)(1e9 + 7);
const int NUM_BIT = 62;
#define FOR(i, a, b) for(int i = a; i <= b; i++)
int n;
long long size[MAX], values[MAX];
void init(){
cin >> n;
FOR(i, 1, n) cin >> size[i] >> values[i];
}
namespace subtask1{
bool check(){
return n <= 16;
}
void solve(){
long long ans = -INF;
FOR(mask, 1, MASK(n) - 1){
long long sumVal = 0, maxSize = 0, minSize = INF;
FOR(i, 0, n - 1) if(BIT(mask, i))
{sumVal += values[i + 1]; maximize(maxSize, size[i + 1]); minimize(minSize, size[i + 1]);}
maximize(ans, sumVal - (maxSize - minSize));
}
cout << ans;
}
}
namespace subtask2{
bool check(){
return n <= 500000;
}
pair <long long, long long> arts[MAX];
long long sum[MAX];
void solve(){
FOR(i, 1, n) arts[i] = make_pair(size[i], values[i]);
sort(arts + 1, arts + n + 1);
long long ans = -INF;
long long mi = INF;
FOR(i, 1, n){
sum[i] = sum[i - 1] + arts[i].se;
minimize(mi, sum[i - 1] - arts[i].fi);
maximize(ans, sum[i] - arts[i].fi - mi);
}
cout << ans;
}
}
void solve(){
// if(subtask1::check()){subtask1::solve(); return;}
if(subtask2::check()){subtask2::solve(); return;}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
// #define test "test"
// freopen(test".inp", "r", stdin);
// freopen(test".out", "w", stdout);
srand(time(0));
int t = 1;
while(t--){
// gen();
init();
solve();
}
return 0;
}
/*** ROAD TO VOI 2025 ***/
