1 import java.util.*;
 2 import java.io.*;
 3 class Main
 4 {
 5  static int[][] map = null;
 6  static int pointNum;
 7  
 8  public static void main(String[] arge) throws IOException
 9  {
10   Scanner input = new Scanner(System.in);
11   BufferedReader cin = new BufferedReader(new InputStreamReader(System.in));
12   pointNum = input.nextInt();
13 
14   map = new int[pointNum+1][pointNum+1];
15   int max = 0,value = 0;
16 
17   for(int i = 0;i<map.length;i++)
18    Arrays.fill(map[i],Integer.MAX_VALUE/2);
19 
20   for(int i = 1;i<pointNum;i++)
21   {
22    String str = cin.readLine();
23 
24    String[] num = str.split(" ");
25    
26    map[Integer.parseInt(num[0])][Integer.parseInt(num[1])] = Integer.parseInt(num[2]);
27    map[Integer.parseInt(num[1])][Integer.parseInt(num[0])] = Integer.parseInt(num[2]);
28    
29   }
30 
31   doWork();
32 
33   for(int i = 1;i<map.length;i++)
34    for(int j = i+1;j<map.length;j++)
35    {
36     if(map[i][j]<=Integer.MAX_VALUE/2)
37      max = map[i][j] > max ? map[i][j]:max;
38    }
39    
40 
41   for(int i = 1;i<=max;i++)
42   {
43     value = value + i + 10;
44   }
45   
46   sop1(value);
47  }
48  
49  public static void doWork()
50  {
51   for(int k = 1;k<pointNum;k++)
52   {
53    for(int i = 1;i<map.length;i++)
54    {
55     for(int j = 1;j<map.length;j++)
56     {
57      
58      if(map[i][k] + map[k][j] < map[i][j])
59       map[i][j] = map[i][k] + map[k][j];
60     }
61    }
62   }
63  }
64  
65  public static void sop1(Object obj)
66  {
67   System.out.println(obj);
68  }
69 }