#include <atcoder/dsu>
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

void solve() {
  ll n, m;
  cin >> n >> m;
  priority_queue<tuple<ll, ll, ll>> que;
  rep(i, m) {
    ll a, b, c;
    cin >> a >> b >> c, a--, b--;
    que.emplace(c, a, b);
  }
  ll ans = 0;
  atcoder::dsu dsu(n);
  while (!que.empty()) {
    auto [c, a, b] = que.top();
    que.pop();
    if (!dsu.same(a, b)) {
      ans += c;
      dsu.merge(a, b);
    }
  }
  ans *= 2;
  cout << ans << '\n';
}

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);
  int T = 1;
  for (int t = 0; t < T; t++) {
    solve();
  }
  return 0;
}