#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
int n, ans=0;
vector<int> psum;
vector<pii> vect;
void dnc(int l, int r, int optl, int optr){
if (l>r)return;
int mid=(l+r)/2, opt, best=LLONG_MIN/2;
for (int i=optl; i<=min(mid, optr); ++i)if (psum[mid]-psum[i-1]-vect[mid].fi+vect[i].fi>best)best=psum[mid]-psum[i-1]-vect[mid].fi+vect[i].fi, opt=i;
ans=max(ans, best);
dnc(l, mid-1, optl, opt);
dnc(mid+1, r, opt, optr);
}
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n;
vect.resize(n+1);
psum.resize(n+1, 0);
for (int i=1; i<=n; ++i)cin>>vect[i].fi>>vect[i].se;
sort(vect.begin()+1, vect.end());
for (int i=1; i<=n; ++i)psum[i]=psum[i-1]+vect[i].se;
dnc(1, n, 1, n);
cout<<ans;
}
