void prim()
{
    int i,j;
    for(i=1;i<n;i++)
    {
        if(visit[2]) break;
        else
        {
         double max=MAX;
         int k=1;
         for(j=2;j<=n;j++)
         if(visit[j]==0&&dis[j]<max) {max=dis[j];k=j;}
         visit[k]=1;   
         if(max>ans) ans=max; 
         for(j=2;j<=n;j++)
         if(visit[j]==0&&len(k,j)<dis[j])
         dis[j]=len(k,j);
        }
    }
    printf("Scenario #%d\n",cases);cases++;
    printf("Frog Distance = %.3lf\n\n",ans);
}