#include<bits/stdc++.h>
#include<atcoder/all>
#ifdef LOCAL
#include <debug_print.hpp>
#define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (static_cast<void>(0))
#endif
using namespace atcoder;
using mint=modint1000000007;
using namespace std;
using ll=long long;
using ul=unsigned long long;
int dx[8] = {1, 0, -1, 0, -1, -1, 1, 1};
int dy[8] = {0, 1, 0, -1, -1, 1, -1, 1};
using Graph=vector<vector<int>>;
int main(){
    int N,M;
    cin>>N>>M;
    vector<tuple<ll,int,int>>T(M);
    for(auto&[c,a,b]:T)cin>>a>>b>>c,a--,b--;
    sort(T.rbegin(),T.rend());
    ll ans=0;
    dsu uf(N);
    for(auto[c,a,b]:T){
        if(!uf.same(a,b))ans+=c,uf.merge(a,b);
    }
    cout<<ans*2<<endl;
}