#include <bits/stdc++.h>
using namespace std;
#define MOD 1000000007
#define mxn 500005
#define mxm 1005
#define f first
#define s second
#define pb push_back
#define es " "
#define endl '\n'
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3f
#define ll long long
#define fastio ios_base::sync_with_stdio(0), cin.tie(0)
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
typedef pair<ll, ll> pii;
typedef pair<pii, int> pip;
int n;
ll resp;
pii v[mxn];
int main(){
fastio;
cin >> n;
for(int i=1; i<=n; i++){
cin >> v[i].f >> v[i].s;
}
sort(v+1, v+1+n);
for(int i=1; i<=n; i++){
ll sum=0, take;
for(int j=i; j<=n; j++){
sum+=v[j].s;
take=v[j].f-v[i].f;
resp=max(resp, sum-take);
}
}
cout << resp;
return 0;
}
