/**
____ ____ ____ ____ ____
||a |||t |||o |||d |||o ||
||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|
**/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N_MAX = 500000;
struct Artwork {
ll dim, val;
};
bool operator < (const Artwork &a, const Artwork &b) {
return a.dim < b.dim;
}
int N;
Artwork art[N_MAX + 2];
int main () {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> N;
for (int i = 1; i <= N; i++) {
cin >> art[i].dim >> art[i].val;
}
sort(art + 1, art + N + 1);
ll answer = 0;
ll pref = 0;
ll mx = LLONG_MIN / 2;
for (int i = 1; i <= N; i++) {
mx = max(mx, art[i].dim - pref);
pref += art[i].val;
answer = max(answer, pref - art[i].dim + mx);
}
cout << answer << "\n";
return 0;
}
