#include <bits/stdc++.h>
using namespace std;
#define int long long
#define endl '\n'
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("O3")
class Solve {
public:
void solve() {
int tuxn;
cin >> tuxn;
vector<pair<int,int>> tuxv(tuxn);
for (int tuxi = 0; tuxi < tuxn; tuxi++) {
int tuxa, tuxb;
cin >> tuxa >> tuxb;
tuxv[tuxi] = {tuxa, tuxb};
}
sort(tuxv.begin(), tuxv.end());
int tuxans = LLONG_MIN;
int tuxsum = 0, tuxl = 0;
for (int tuxr = 0; tuxr < tuxn; tuxr++) {
tuxsum += tuxv[tuxr].second;
tuxans = max(tuxans, tuxsum - (tuxv[tuxr].first - tuxv[tuxl].first));
}
cout << tuxans << endl;
}
};
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
Solve tuxz;
tuxz.solve();
}
