#include <bits/stdc++.h>
#include <ext/rope>
using namespace std;
using namespace __gnu_cxx;
#pragma GCC optimize("-Ofast")
#pragma GCC optimize("-O1")
//-------------------------------------------------------------//
typedef long long ll;
typedef unsigned long long ull;
#define fast ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define PI acos(-1)
#define lb lower_bound
#define ub upper_bound
#define endl '\n'
#define all(v) v.begin(),v.end()
#define allr(v) v.rbegin(),v.rend()
#define sum_to(n) (n*(n+1))/2
#define pb push_back
#define pf push_front
#define sz size()
#define fil(arr,x) memset(arr,x,sizeof(arr))
const ll mod=1e9+7;
int dx[8]={0,1,0,-1,1,1,-1,-1};
int dy[8]={1,0,-1,0,1,-1,-1,1};
//-------------------------------------------------------------//
ll lcm(ll a,ll b)
{
return (max(a,b)/__gcd(a,b))*min(a,b);
}
void person_bool(bool x)
{
cout<<(x?"YES":"NO")<<endl;
}
int n;
vector<pair<ll,ll>>arr;
int main()
{
//freopen("input.txt","r",stdin);
//freopen("output.txt","w",stdout);
fast
cin>>n;
arr.resize(n);
for(int i=0;i<n;i++){
cin>>arr[i].first>>arr[i].second;
}
sort(all(arr));
ll ans=0;
ll sum=arr[0].second;
for(int i=0;i<n;i++){
ans=max(ans,arr[i].second);
}
vector<ll>v(n);
for(int i=1;i<n;i++){
sum+=arr[i].second;
v[i]=sum-(arr[i].first-arr[0].first);
ans=max(ans,v[i]);
}
for(int i=n-2;i>=0;i--){
v[i]=max(v[i],v[i+1]);
}
ll x=0;
for(int i=1;i<n;i++){
x-=arr[i-1].second;
x+=arr[i].first-arr[i-1].first;
ans=max(ans,v[i]+x);
}
cout<<ans<<endl;
return 0;
}
