#include<bits/stdc++.h>
using namespace std;
const int maxm = 200005;
const int inf = 0x3f3f3f3f;
struct edge{int v, w, next;
}e[maxm << 1];
int cnt, n, m, sum, t, p, now = 1;
int dis[5005], head[maxm], vis[5005];
int a, b, c;void add(int uu, int vv, int ww)
{e[++cnt].v = vv;e[cnt].w = ww;e[cnt].next = head[uu];head[uu] = cnt;
}
int main()
{cin >> n >> m;for(int i = 1; i <= m; i++){cin >> a >> b >> c;add(a, b, c); add(b, a, c);}for(int i = 1; i <= n; i++)dis[i] = inf;for(int i = head[1]; i; i = e[i].next)dis[e[i].v] = min(e[i].w, dis[e[i].v]);while(++t < n){vis[now] = 1;int minn = inf;now = -1;for(int i = 1; i <= n; i++){if(!vis[i] && minn > dis[i]){minn = dis[i];now = i;}}if(now == -1) {cout << "impossible";return 0;}sum += minn;for(int i = head[now]; i; i = e[i].next){if(!vis[e[i].v] && e[i].w < dis[e[i].v])dis[e[i].v] = e[i].w;}}cout << sum;return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int maxm = 200005;
const int inf = 0x3f3f3f3f;
struct edge{int v, w, next;
}e[maxm << 1];
int cnt, n, m, sum, t, p, now = 1;
int dis[5005], head[maxm], vis[5005];
int a, b, c;void add(int uu, int vv, int ww)
{e[++cnt].v = vv;e[cnt].w = ww;e[cnt].next = head[uu];head[uu] = cnt;
}
int main()
{cin >> n >> m;for(int i = 1; i <= m; i++){cin >> a >> b >> c;add(a, b, c); add(b, a, c);}for(int i = 1; i <= n; i++)dis[i] = inf;for(int i = head[1]; i; i = e[i].next)dis[e[i].v] = min(e[i].w, dis[e[i].v]);while(++t < n){vis[now] = 1;int minn = inf;for(int i = 1; i <= n; i++){if(!vis[i] && minn > dis[i]){minn = dis[i];now = i;}}if(dis[now] == inf) {cout << "orz";return 0;}sum += minn;for(int i = head[now]; i; i = e[i].next){if(!vis[e[i].v] && e[i].w < dis[e[i].v])dis[e[i].v] = e[i].w;}}cout << sum;return 0;
}