#include <bits/stdc++.h>
#define int long long
#define FOR(var,bound) for(int var = 0; var < bound; var++)
#define FORB(var,lb,ub) for (int var = lb; var < ub; var++)
#define FORR(var,bound) for(int var = bound-1; var >= 0; var--)
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef pair<int, int> pii;
int n;
pii art[500000];
int prefixValue[500005];
int getValue(int l, int r) {
int s = prefixValue[r+1] - prefixValue[l];
return s - (art[r].first - art[l].first);
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin >> n;
FOR(i, n) {
cin >> art[i].first >> art[i].second;
}
sort(art, art + n);
prefixValue[0] = 0;
FOR(i, n) {
prefixValue[i+1] = prefixValue[i] + art[i].second;
}
int res = 0;
FOR(i, n) {
FORB(j, i, n) {
res = max(res, getValue(i, j));
}
}
cout << res << endl;
}
