#include <iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<climits>
#include<vector>
using namespace std;
const int maxn=1005;

double dis[maxn];
bool vis[maxn];
int x[maxn],y[maxn];
int i,j,n,t;
double sum;
struct node
{
    int num;
    double d;
   node(int a,double b){num=a; d=b;}
};
vector<node> s[maxn];

bool prim()
{
    sum=0;
    bool flag=0;
    int k;
    vis[1]=1;
    for(int i=0;i<s[1].size();i++) dis[s[1][i].num]=s[1][i].d;
    for(int i=1;i<n;i++)
    {
        double minn=INT_MAX*1.0;
        for(int j=1;j<=n;j++)
            if(!vis[j] && minn>dis[j])
            {