1 #include<iostream>
 2 #include<cstdio>
 3 #include<algorithm>
 4 #include<vector>
 5 using namespace std;
 6 int f[100086];
 7 struct edge
 8 {
 9     int from;
10     int to;
11     int weight;
12 };
13 int n, m;
14 int tot;
15 long long ans;
16 vector<edge>e;
17 int find(int x)//普通的并查集
18 {
19     if (f[x] == x)
20         return x;
21     else
22         return f[x] = find(f[x]);
23 }
24 void merge(int a, int b)
25 {
26     int x = find(a);
27     int y = find(b);
28     if (f[x] != f[y])
29         f[y] = x;
30 }
31 bool cmp(edge a, edge b)
32 {
33     return a.weight < b.weight;
34 }
35 int main()
36 {
37     cin >> n >> m;
38     for (int i = 1; i <= n; i++)
39         f[i] = i;//并查集初始化
40     for (int i = 1; i <= m; i++)
41     {
42         int x, y, z;
43         cin >> x >> y >> z;
44         edge t;
45         t.from = x;
46         t.to = y;
47         t.weight = z;
48         e.push_back(t);
49         t.from = y;
50         t.to = x;
51         e.push_back(t);
52     }
53     sort(e.begin(), e.end(), cmp);
54     for (int i = 0; i < e.size(); i++)
55     {
56         if (find(e[i].from) != find(e[i].to))
57         {
58             merge(e[i].from, e[i].to);
59             ans += e[i].weight;
60         }
61     }
62     cout << ans << endl;
63     return 0;
64 }