#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
typedef long long ll;
using namespace std;
using namespace __gnu_pbds;
#define FOR(i, x, y) for(ll i=x; i<y; i++)
#define FORNEG(i, x, y) for(ll i=x; i>y; i--)
#define ordered_set tree<ll, null_type,less_equal<ll>, rb_tree_tag,tree_order_statistics_node_update>
#define fast() ios_base::sync_with_stdio(false);cin.tie(NULL)
int main(){
fast();
ll n; cin >> n;
vector<vector<ll>> paintings;
FOR(i,0,n){
ll a,b;
cin >> a >> b;
paintings.push_back({a,b});
}
sort(paintings.begin(), paintings.end());
ll curmax=-1, curmin=1000000000000000000, cur=0, ans=0;
FOR(i,0,n){
curmax = max(curmax, paintings[i][0]);
curmin = min(curmin, paintings[i][0]);
cur += paintings[i][1];
if (cur-(curmax-curmin)<paintings[i][1]){
curmax = paintings[i][0];
curmin = paintings[i][0];
cur = paintings[i][1];
}
ans = max(ans, cur-(curmax-curmin));
}
cout << ans;
}
