#pragma GCC optimize("O3")
#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 tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> indexed_set;
typedef tree<int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> indexed_multiset;
#define int long long
#define double long double
#define pb push_back
#define fastio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define debug(x) cout << #x << " = " << x << '\n';
#define vdebug(a) cout << #a << " = "; for(auto x : a) cout << x << " "; cout << '\n';
const double eps = 1e-9;
const int mod = 1e9 + 7;
const int N = 2e5 + 5;
const int INF = 1e18;
signed main(){
fastio;
int n;
cin >> n;
vector<pair<int, int>> v(n + 1, {0, 0});
for(int i = 1; i <= n; i++){
cin >> v[i].first >> v[i].second;
}
sort(v.begin(), v.end());
vector<int> pref(n + 1, 0);
for(int i = 1; i <= n; i++){
pref[i] = pref[i - 1] + v[i].second;
}
// (pref[r] - pref[l - 1] - (a[r] - a[l]))
// (pref[r] - pref[l - 1] - a[r] + a[l])
// ((pref[r] - a[r]) + (a[l] - pref[l]))-in max qiymetini tapmaliyig
vector<int> x(n + 1, 0); // x[i] --> i-ci indexe qeder (a[l] - pref[l]))-in en boyuk qiymeti
for(int i = 1; i <= n; i++){
x[i] = max(x[i - 1], v[i].first - pref[i - 1]);
}
int ans = 0;
for(int i = 1; i <= n; i++){
ans = max(ans, (pref[i] - v[i].first) + (x[i]));
}
cout << ans << '\n';
}
/*
freopen("x.in", "r", stdin);
freopen("x.out", "w", stdout);
*/
//atilla
