#include<bits/stdc++.h>
using namespace std;
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define ll long long int
const ll N = 100+5 , INF = 1e18 , MOD = 1e9+7;
void solve(){
ll n;
cin >> n;
vector<pair<ll,ll>> dish(n+5);
for(ll i = 1; i <= n; i++) cin >> dish[i].first >> dish[i].second;
sort(dish.begin()+1,dish.begin()+n+1);
vector<ll> presum(n+5);
for(ll i = 1; i <= n; i++) presum[i] = presum[i-1]+dish[i].second;
multiset<ll> s;
for(ll i = 1; i <= n; i++) s.insert(presum[i]-dish[i].first);
ll ans = -INF;
for(ll i = 1; i <= n; i++){
ans = max(ans,(*(s.rbegin()))+dish[i].first-presum[i-1]);
s.erase(s.find(presum[i]-dish[i].first));
}
cout << ans;
}
int main(){
fast;
ll tc = 1;
// cin >> tc;
while(tc--) solve();
return 0;
}
