19975116 2017-03-03 08:53:42 Accepted 1162 0MS 1524K 1304 B G++ 
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <algorithm>

using namespace std;

struct point
{
    int x,y;
    double l;
}p[11000];
int parent[110],n;
double x[110],y[110];
bool cmp(point a, point b)
{
    return a.l < b.l;
}
int find(int x)
{
    int s,tmp;
    for (s = x; parent[s] >= 0; s = parent[s]);
    while (s != x)
    {
        tmp = parent[x];
        parent[x] = s;
        x = tmp;
    }
    return s;
}
void Union(int A, int B)
{
    int a = find(A), b = find(B);
    int tmp = parent[a]+parent[b];
    if (parent[a] < parent[b])
    {
        parent[b] = a;
        parent[a] = tmp;
    }
    else
    {
        parent[a] = b;
        parent[b] = tmp;
    }
} 
void kruskal(int k)
{
    double sum = 0;
    int u,v,i,j = 0;
    memset(parent,-1,sizeof(parent));
    for (i = 0; i <= k; i ++)
    {
        u = p[i].x;    v = p[i].y;
        if (find(u) != find(v))
        {
            sum += p[i].l;
            Union(u,v);
            j ++;
        }
        if (j == n-1) break;
    }
    printf("%.2lf\n",sum);
}
int main ()
{
    int i,j,k;
    while (scanf("%d",&n)!=EOF)
    {
        k = -1;
        for (i = 1; i <= n; i ++)
            scanf("%lf%lf",x+i,y+i);
        for (i = 1; i < n; i ++)
        for (j = 1+i; j <= n; j ++)
        {
            p[++ k].x = i;
            p[k].y = j;
            p[k].l = sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
        }
        sort(p,p+k+1,cmp);
        kruskal(k);
    }
    return 0;
}