#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <string>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <fstream>
#include <cassert>
#include <cstring>
#include <numeric>
#include <ctime>
#include <complex>
#include <bitset>
#include <random>
#include <climits>
#include <stack>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx,avx2,tune=native")
using namespace std;
typedef long long ll;
typedef long double ld;
#define int ll
#define double ld
#define loop(i, n) for(int i = 0; i < (int)n; ++i)
#define loop1(i, n) for(int i = 1; i <= (int)n; ++i)
#define F first
#define S second
#define pb push_back
#define pi pair <int, int>
#define all(x) begin(x), end(x)
#define ti tuple <int, int, int>
#define Point Vect
#define no {cout << -1; return;}
#define yes {cout << "Yes"; return;}
#define mkp make_pair
#define mkt make_tuple
#define cerr if(0) cerr
const int N = 5e5 + 7;
pi t[4 * N];
void change(int v, int l, int r, int pos, int val) {
if (l == r) {
t[v] = { val, val };
return;
}
int m = l + r >> 1;
if (m >= pos)
change(2 * v + 1, l, m, pos, val);
else
change(2 * v + 2, m + 1, r, pos, val);
t[v] = { t[2 * v + 1].F + t[2 * v + 2].F, max(t[2 * v + 1].S, t[2 * v + 1].F + t[2 * v + 2].S) };
}
void solve() {
int n; cin >> n;
vector <pi> p(n);
loop(i, n)
cin >> p[i].F >> p[i].S;
sort(all(p));
change(0, 0, n - 1, 0, p[0].S);
loop1(i, n - 1)
change(0, 0, n - 1, i, p[i].S - (p[i].F - p[i - 1].F));
int ans = p.back().S;
loop(i, n - 1) {
ans = max(ans, t[0].S);
change(0, 0, n - 1, i, 0);
change(0, 0, n - 1, i + 1, p[i + 1].S);
}
cout << ans;
}
signed main() {
//freopen("b2.txt", "r", stdin);
//freopen("ans9.txt", "w", stdout);
ios::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
//int t; cin >> t; loop(i, t)
solve();
return 0;
}
