//#pragma GCC optomize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("O3")
//#pragma GCC target("avx2")
//#pragma GCC target("sse,sse2,sse4.1,sse4.2")
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define max_heap priority_queue<pair <ll, pair <ll, ll>>>
#define min_heap priority_queue<pair <ll, pair <ll, ll>>, vector<pair <ll, pair <ll, ll>>>, greater<pair <ll, pair <ll, ll>>>>
//#define min_heap priority_queue<ll, vector<ll>, greater<ll>>
#define sariE cin.tie(NULL); cout.tie(NULL); ios_base::sync_with_stdio(false);
#define filE freopen("in.txt", "r", stdin); freopen("out1.txt", "w", stdout);
#define endl '\n'
#define md(a) (a % mod + mod) % mod
#define pb push_back
//cout << vectorprecision(5) << fixed << f;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll const maxn = 5e5 + 123;
ll const inf = 2e18;
ll const loG = 23;
ll const mod = 1e9 + 7;
//ll const mod = 998244353;
ll const sq = 350;
ll power(ll a, ll b, ll mod){if(b==0)return 1;if(b==1)return a;ll x = power(a, b / 2, mod);return (((x * x) % mod) * (b % 2 ? a : 1)) % mod;}
ll n, dp[maxn], ps[maxn], mx[maxn], ans;
vector <pair <ll, ll>> arr;
void Solve(){
cin >> n;
for (int i = 1; i < n + 1; i++){
ll a, b; cin >> a >> b;
arr.pb({a, b});
}
arr.pb({0, 0});
sort(arr.begin(), arr.end());
for (int i = 1; i < n + 1; i++){
ps[i] = ps[i - 1] + arr[i].second;
dp[i] = arr[i].second;
dp[i] = max(dp[i], ps[i] - arr[i].first + mx[i - 1]);
mx[i] = max(mx[i - 1], arr[i].first - ps[i - 1]);
ans = max(ans, dp[i]);
}
cout << ans << endl;
}
int main(){
sariE;// filE;
int test = 1;
//cin >> test;
while (test--) Solve();
return 0;
}
