#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001LL

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