#include <bits/stdc++.h>
using namespace std;
typedef long long ll ;
#define AC cin.sync_with_stdio(0),cin.tie(0);
int parent[10000];
struct point{
ll x,y;//coords
};
struct line{
point a,b;//2 points
ll w;//weight
};
bool cmp(line a, line b){
return a.w<b.w;
}
int FindParent(int i){
if(parent[i]==-1) return i;
else return FindParent(parent[i]);
}
int main(){
//kruskal->get all line
AC
ll n,x,y,ans=0;
cin>>n;
for(int i=0;i<n;i++) parent[i] = -1;
vector<line> vec;
point p[10000];
line tmp;
//get all lines
for(int i=0;i<n;i++){
cin>>x>>y;
p[i].x=x;
p[i].y=y;
for(int j=0;j<i;j++){
tmp.a=p[j];
tmp.b=p[i];
//index of point b must be bigger than a
tmp.w=( abs(p[i].x-p[j].x) + abs(p[i].y - p[j].y));
vec.push_back(tmp);
}
}
sort(vec.begin(),vec.end(),cmp);
//kruskal
for(int i=0;i<vec.size();i++){
x=FindParent(vec[i].a);
y=FindParent(vec[i].b);
if(x!=y){
ans+=vec[i].w;
parent[x]=y;
}
}
cout<<ans<<"\n";
}
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