#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
struct Artwork {
long long a, b;
};
bool compareArt(const Artwork& x, const Artwork& y) {
return x.a < y.a;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n;
cin >> n;
vector<Artwork> arts(n);
for (int i = 0; i < n; i++) {
cin >> arts[i].a >> arts[i].b;
}
sort(arts.begin(), arts.end(), compareArt);
long long max_ans = -2e18;
long long current_sum = 0;
long long prev_min_val = 0;
long long temp_max = -2e18;
for (int i = 0; i < n; i++) {
current_sum += arts[i].b;
if (i == 0) {
temp_max = arts[i].b;
} else {
temp_max = max(arts[i].b, temp_max + arts[i].b - (arts[i].a - arts[i-1].a));
}
max_ans = max(max_ans, temp_max);
}
cout << max_ans << endl;
return 0;
}
