#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define pii pair<int,int>
#define sz size()
#define all(v) v.begin(),v.end()
#define fi first
#define se second
const int N = 2e5;
const int mod = 1e9+7;
const ll INF = 1e18;
const int di[] = {1, -1, 0, 0};
const int dj[] = {0, 0, 1, -1};
ll a[N+1],b[N+1],ind[N+1];
bool cmp(int i,int j){
if(a[i]==a[j])
return b[i]<b[j];
return a[i]<a[j];
}
void solve() {
int n;
cin>>n;
for(int i = 1; i <= n; i++){
cin>>a[i]>>b[i];
ind[i]=i;
}
sort(ind+1,ind+n+1,cmp);
ll ans=0;
for(int i = 1; i <= n; i++){
ll x=0;
for(int j = i; j <= n; j++){
x+=b[ind[j]];
ans=max(ans,x-(a[ind[j]]-a[ind[i]]));
}
}
cout<<ans<<"\n";
}
int main() {
//freopen("cowrun.in","r",stdin);
//freopen("cowrun.out","w",stdout);
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int t=1;
//cin>>t;
while(t--) {
solve();
}
return 0;
}
