#include<iostream>
#include<iomanip>
#include<algorithm>
#include<stack>
#include<queue>
#include<string>
#include<string.h>
#include<cmath>
#include<vector>
#include<map>
#include<unordered_map>
#include<set>
#include<unordered_set>
#include<cstdio>
#include<bitset>
#include<chrono>
#include<random>
#include<ext/rope>
/* ordered_set
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
*/
#define int long long
#define pb push_back
#define fi first
#define se second
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
const int maxN = 1e6 + 5;
const int mod = 1e9 + 7;
const ll oo = 1e18;
int n;
pair<int, int> a[maxN];
void ReadInput()
{
cin >> n;
for(int i=1; i<=n; i++) cin >> a[i].fi >> a[i].se;
sort(a + 1, a + n + 1);
}
void Solve()
{
ll sum = 0;
ll res = 0, _min = 0;
for(int i=1; i<=n; i++)
{
_min = min(_min, sum - a[i].fi);
sum += a[i].se;
int val = sum - a[i].fi - _min;
res = max(res, val);
}
cout << res;
}
int32_t main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
ReadInput();
Solve();
}
