1197.cpp

// Authored by : BaaaaaaaaaaarkingDog
// Co-authored by : -
// http://boj.kr/aaafcfd71b164a75a8b89343bef17a46
#include <bits/stdc++.h>
using namespace std;

vector<int> p(10005,-1);

int find(int x){
  if(p[x] < 0) return x;
  return p[x] = find(p[x]);
}

bool is_diff_group(int u, int v){
  u = find(u); v = find(v);
  if(u == v) return 0;
  if(p[u] == p[v]) p[u]--;
  if(p[u] < p[v]) p[v] = u;
  else p[u] = v;
  return 1;
}

int v, e;
tuple<int,int,int> edge[100005];

int main(void) {
  ios::sync_with_stdio(0);
  cin.tie(0);

  cin >> v >> e;
  for(int i = 0; i < e; i++){
    int a, b, cost;
    cin >> a >> b >> cost;
    edge[i] = {cost, a, b};
  }
  sort(edge, edge + e);
  int cnt = 0;
  int ans = 0;
  for(int i = 0; i < e; i++){
    int a, b, cost;
    tie(cost, a, b) = edge[i];
    if(!is_diff_group(a, b)) continue;
    ans += cost;
    cnt++;
    if(cnt == v-1) break;    
  }
  cout << ans;
}