#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define sort undefined_function // To use stable_sort instead sort
#define bpc __builtin_popcount
#define ull unsigned long long
#define ld double
#define ll long long
#define mp make_pair
#define F first
#define S second
# pragma GCC optimize("O2")
//pragma GCC optimize("my solution")
using namespace __gnu_pbds;
using namespace std;
typedef tree<long long, null_type, less_equal<long long>,
rb_tree_tag, tree_order_statistics_node_update> Tree;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll INF = 9223372036854775807LL;
const ll inf = 2147483647;
const ll MOD = 1e9 + 7; //[998244353, 1e9 + 7, 1e9 + 13]
ll gcd(ll a, ll b) {return b ? gcd(b, a % b) : a;}
ll lcm(ll a, ll b) {return a * b / gcd(a, b);}
ll ceil(ll a, ll b) {return (a + b - 1) / b;}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
int n;
cin >> n;
vector<pair<ll, ll>> v(n + 1);
for (int i = 1; i <= n; i ++)
cin >> v[i].F >> v[i].S;
stable_sort(v.begin() + 1, v.end());
ll ans = 0;
for (int i = 1; i <= n; i ++) {
ll sum = 0;
for (int j = i; j <= n; j ++) {
sum += v[j].S;
ans = max(ans, sum - (v[j].F - v[i].F));
}
}
cout << ans << '\n';
return 0;
}
