#include <bits/stdc++.h>
#include <atcoder/dsu>
using namespace std;
using namespace atcoder;
#define int long long

int N,M;
int ans = 0;
vector<tuple<int,int,int>> G;
vector<bool> visited(200001);

signed main(){
  cin>>N>>M;
  dsu d(N+1);
  for(int i = 0; i < M; i++){
    int a,b,c; cin>>a>>b>>c;
    G.push_back(make_tuple(c,a,b));
  }
  sort(G.rbegin(),G.rend());
  for(int i = 0; i < M; i++){
    int a = get<1>(G[i]);
    int b = get<2>(G[i]);
    int c = get<0>(G[i]);
    if(!d.same(a,b)){
      d.merge(a,b);
      ans += c;
    }
  }
  cout << ans*2 << endl;
}