#include <bits/stdc++.h>
using namespace std;
#define int long long
#define FOR(i, l, r) for (int i = (l); i <= (r); ++i)
#define FOD(i, r, l) for (int i = (r), _l = (l); i >= _l; i--)
#define pii pair<int,int>
#define endl '\n'
#define pb push_back
#define TIME (1.0 * clock() / CLOCKS_PER_SEC)
#define Konosuba tuple<int , int , int, int>
#define fi first
#define se second
const int N = 5e5 + 5;
const int MOD = 1e9 + 7;
const int block = 330;
const int LOG = 30;
const int MAXN = 1e6 + 1;
const int INF = 1e14;
const int base = 311;
template<class A, class B>
bool umin(A& var, const B& val){ return (val < var) ? (var = val, true) : false; }
template<class A, class B>
bool umax(A& var, const B& val){ return (var < val) ? (var = val, true) : false; }
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<class X, class Y> int random(const int& l, const int& r) {
return uniform_int_distribution<int>(l,r)(rng);
}
int n;
pii a[N];
int b[N];
int prefixsum[N];
int st[4 * N];
void update(int idx , int l , int r , int pos , int val){
if(l > pos || r < pos) return;
if(l == r){
st[idx] = val;
return;
}
int mid = (l + r) / 2;
update(2 * idx , l , mid , pos ,val);
update(2 * idx + 1 , mid + 1 , r , pos ,val);
st[idx] = max(st[2 * idx] , st[2 * idx + 1]);
}
int get(int idx , int l , int r , int u , int v){
if(l > v || r < u) return 0;
if(u <= l && r <= v){
return st[idx];
}
int mid = (l + r) / 2;
return max(get(2 * idx , l , mid , u , v) , get(2 * idx + 1 , mid + 1 , r , u , v));
}
void solve(void){
cin >> n;
FOR(i , 1 , n) cin >> a[i].first >> a[i].second;
sort(a + 1 , a + n + 1);
int res = 0;
update(1 , 0 , n , 0 , a[1].first);
FOR(i , 1 , n){
prefixsum[i] = prefixsum[i - 1] + a[i].second;
int ans = get(1 , 0 , n , 0 , i - 1) + prefixsum[i] - a[i].first;
//cout << get(1 , 0 , n , 0 , i - 1) << endLL
res = max(res , ans);
update(1 , 0 , n , i , a[i + 1].first - prefixsum[i]);
}
cout << res;
}
signed main(void) {
if (fopen("smod.INP", "r")) {
freopen("smod.INP", "r", stdin);
freopen("smod.OUT", "w", stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int testCase = 1; //cin >> testCase;
FOR(i , 1 , testCase){
solve();
}
cerr << "Time elapsed: " << TIME << "s.\n";
return (0);
}
