#include <iostream>
#include <algorithm>
using namespace std;
long long s,n,r,ss[500010],sd[500010],r2;
struct tablouri{long long a,b;}t[500010];
bool comp(tablouri a1,tablouri b1)
{
return a1.a<b1.a;
}
int main()
{
cin>>n;
for(long long i=1;i<=n;++i)
{
cin>>t[i].a>>t[i].b;
s+=t[i].b;
}
sort(t+1,t+n+1,comp);
r=s-t[n].a+t[1].a;
long long sp=0;
for(long long i=2;i<=n;++i)
{
sp+=t[i-1].b;
ss[i]=t[i].a-sp-t[1].a;
ss[i]=max(ss[i-1],ss[i]);
}
sp=0;
for(long long i=n-1;i>=1;--i)
{
sp+=t[i+1].b;
sd[i]=t[n].a-sp-t[i].a;
sd[i]=max(sd[i],sd[i+1]);
}
for(long long i=1;i<=n;++i)
r2=max(r2,sd[i]+ss[i]);
cout<<r+r2;
return 0;
}
