hihocoder#1109

#include<cstdio>
#include<cctype>
#include<vector>
#include<algorithm>
using namespace std;
int n,m;
long long ans;
vector<pair<int,int> >edge[1000005];
vector<pair<int,int> >e;
bool used[1000005];

inline int read(){
	char ch=getchar();int k=0;
	while(!isdigit(ch)) ch=getchar();
	while(isdigit(ch)){k=(k<<1)+(k<<3)+ch-‘0‘;ch=getchar();}
	return k;
}

bool cmp(pair<int,int>p1,pair<int ,int>p2){return p1.second>=p2.second;}

void prim(){
	used[1]=1;
	for(int i=0;i<edge[1].size();i++) e.push_back(edge[1][i]);
	make_heap(e.begin(),e.end(),cmp);
	for(int k=1;k<n;k++){
		while(used[e[0].first]){
			pop_heap(e.begin(),e.end(),cmp);
			e.pop_back();
		}
		pair<int,int>minn=e[0];
		ans+=minn.second;
		pop_heap(e.begin(),e.end(),cmp);
		e.pop_back();
		used[minn.first]=1;
		for(int i=0;i<edge[minn.first].size();i++) if(!used[edge[minn.first][i].first]) {e.push_back(edge[minn.first][i]);push_heap(e.begin(),e.end(),cmp);}
	}
}

int main(){
	n=read();m=read();
	for(int t=1;t<=m;t++){
		int u=read(),v=read(),w=read();
		edge[u].push_back(make_pair(v,w));
		edge[v].push_back(make_pair(u,w));
	}
	prim();
	printf("%d\n",ans);
	return 0;
}