#include <iostream>#include <cstdio>#include <queue>#include <cmath>using namespace std;struct point{ double x,y; int id;}p[110];struct way{ int from,to; double len;};way w[10010];priority_queue <way>pq;int father[110];double sum;bool operator<( const way&a,const way&b ){ return a.len>b.len;}int find_set( int a ){ if( father[a]!=a ) { father[a]=find_set( father[a] ); } return father[a];}void union_set( int a,int b,double c ){ if( a==b ) return; father[b]=a; sum+=c;}int main(){ int n,i,j; way temp; while( scanf("%d",&n)!=EOF ) { for( i=0;i<n;i++ ) { scanf( "%lf%lf",&p[i].x,&p[i].y ); p[i].id=i ; father[i]=i; } for( i=0;i<n;i++ ) { for( j=i+1;j<n;j++ ) { temp.from=p[i].id; temp.to=p[j].id; temp.len=sqrt( ( p[i].x-p[j].x )*( p[i].x-p[j].x )+( p[i].y-p[j].y )*( p[i].y-p[j].y ) ); pq.push( temp ); } } sum=0.0; while( !pq.empty() ) { temp=pq.top(); pq.pop(); union_set( find_set(temp.from),find_set(temp.to),temp.len ); } printf( "%.2lfn",sum ); } return 0;}
