#include <bits/stdc++.h>
#include <atcoder/all>
#include <boost/multiprecision/cpp_dec_float.hpp>
#include <boost/multiprecision/cpp_int.hpp>
namespace mp = boost::multiprecision;
using Bint = mp::cpp_int;
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int n, m;
    cin >> n >> m;
    vector<tuple<int, int, int>> vs;
    rep(i,m) {
        int a, b, c;
        cin >> a >> b >> c;
        vs.emplace_back(c, a-1, b-1);
    }
    sort(vs.rbegin(),vs.rend());
    ll ans = 0;
    dsu uf(n);
    rep(i,m) {
        auto [c, a, b] = vs[i];
        if(uf.same(a,b)) continue;
        uf.merge(a,b);
        ans += c;
    }
    cout << ans*2 << endl;
    return 0;
}