#include<bits/stdc++.h>
#define ll long long
#define ld long double
#define pll pair<ll,ll>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
using namespace std;
#define LOCALIO "C:/Users/admin/Documents/Code/"
pll a[500005];
vector <ll> num;
int main()
{
#ifdef LOCAL
freopen( LOCALIO "input.txt","r",stdin) ;
freopen( LOCALIO "output.txt","w",stdout) ;
#endif
ios_base::sync_with_stdio(NULL); cin.tie(nullptr); cout.tie(nullptr);
// freopen("FIBONACCI.inp","r",stdin);
// freopen("FIBONACCI.out","w",stdout);
ll n; cin >> n;
for (ll i=1; i<=n; i++)
cin >> a[i].fi >> a[i].se;
sort(a+1, a+n+1);
for (ll i=1; i<=n; i++)
a[i].se+=a[i-1].se;
ll ans=0, Min=1e18;
for (ll i=1; i<=n; i++)
{
Min=min(Min, a[i-1].se-a[i].fi);
ans=max(ans, a[i].se-a[i].fi-Min);
}
cout << ans;
}
