#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define PUB push_back
struct art{
ll sz, val;
};
int N;
ll pref[500005], ans = 0;
vector<art> data;
ll sliding_window(int len){
ll ret = 0;
for(int i=1;i+len-1<=N;i++){
ll tmp = (pref[i+len-1]-pref[i-1])-(data[i+len-1].sz-data[i].sz);
ret = max(ret, tmp);
}
return ret;
}
bool comp(art a, art b){
if(a.sz == b.sz) return a.val < b.val;
return a.sz < b.sz;
}
int main(){
cin >> N;
data.PUB({0,0});
for(int i=1;i<=N;i++){
ll a, b;
cin >> a >> b;
data.PUB({a, b});
}
sort(data.begin(), data.end(), comp);
for(int i=1;i<=N;i++) pref[i] = pref[i-1]+data[i].val;
int l=1, r=N;
while(l<=r){
int m = (l+r)/2;
ll tmp = sliding_window(m);
if(tmp > ans) l = m+1;
else r = m-1;
ans = max(tmp, ans);
}
cout << ans << endl;
}
