#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 value[500000], prefix[500000], midx[500000];
int cp[500001];
int getRes(int l, int r) {
return cp[r+1] - cp[l] - 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);
FOR (i, n) {
cp[i + 1] = cp[i] + art[i].second;
}
value[0] = 0;
FORB(i, 1, n) {
value[i] = art[i].second - (art[i].first - art[i-1].first);
prefix[i] = prefix[i - 1] + value[i];
}
int maxIdx = -1;
FORR(i, n) {
midx[i] = maxIdx;
if (maxIdx == -1 || prefix[i] > prefix[maxIdx]) {
maxIdx = i;
}
}
int res = 0;
FOR(i, n - 1) {
res = max(res, getRes(i, midx[i]));
//cout << i << " " << midx[i] << " " << res << endl;
}
cout << res << endl;
}
