#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define pii pair<int,int>
#define pll pair<ll,ll>
#define fi first
#define se second
const int maxN=5e5+5;
const ll inf=2e18;
int n;
pll p[maxN+1];
int main()
{
//freopen("","r",stdin);
//freopen("","w",stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>p[i].fi>>p[i].se;
}
sort(p+1,p+n+1,[&](pll x,pll y)
{
if(x.fi==y.fi)
{
return x.se>y.se;
}
return x.fi<y.fi;
});
ll sum=0,ans=-inf,mn=0;
for(int i=1;i<=n;i++)
{
mn=min(mn,sum-p[i].fi);
sum+=p[i].se;
ans=max(ans,sum-p[i].fi-mn);
//cout<<i<<" "<<ans<<" "<<mn<<'\n';
}
cout<<ans;
}
