#include <bits/stdc++.h>
#define int long long
//#define cout cout << "Test: "
int sum=0;
#define pb push_back
using namespace std;
void solve(){
int n;cin>>n;
vector<pair<int,int>> v(n);
vector<int> ans(n);
for(int i=0;i<n;i++){
int a,b;cin>>a>>b;
v[i]=make_pair(a,b);
}
int maxi=-1;
for(int i=0;i<n;i++){
maxi=max(maxi,v[i].second);
}
int max2=-1;
int ind1,ind2;
for(int i=0;i<n;i++){
for(int j=i+1;j<n;j++){
if(v[i].second+v[j].second-(max(v[i].first,v[j].first)-min(v[i].first,v[j].first))>max2){
max2=v[i].second+v[j].second-(max(v[i].first,v[j].first)-min(v[i].first,v[j].first));
ind1=v[i].first,ind2=v[j].first;
}
//cout<<maxi<<' '<<j<<' '<<i<<endl;
}
}
sum=max2;
for(int i=0;i<n;i++){
if(v[i].first>min(ind1,ind2)&&v[i].first<max(ind1,ind2)){
sum+=v[i].second;
}
}
//cout<<maxi<<' '<<sum<<' '<<max2<<endl;
cout<<max(maxi,max(max2,sum));
}
signed main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
int t=1;
//cin>>t;
while(t--){
solve();
//cout<<endl;
}
return 0;
}
