#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef pair<int, int> ii;
signed main() {
int n, pos, length;
cin >> n;
vector<ii> art(n, ii(0, 0));
for (int i = 0; i < n; ++i) {
cin >> art[i].first >> art[i].second;
}
sort(art.begin(), art.end());
vector<int> prefixval(n, 0);
prefixval[0] = art[0].second;
for (int i = 1; i < n; ++i) {
prefixval[i] = prefixval[i - 1] + art[i].second;
}
int maxval = 0, valsum = 0;
for (int i = 0; i < n; ++i) {
for (int j = i + 1; j < n; ++j) {
if (i > 0) {
valsum = prefixval[j] - prefixval[i - 1];
} else {
valsum = prefixval[j];
}
maxval = max(maxval, valsum - art[j].first + art[i].first);
}
}
cout << maxval << '\n';
return 0;
}
