// compile: make data
// run: ./data < data.in
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#ifdef LOCAL
#include <debug/codeforces.h>
#define debug(x...) _debug_print(#x, x);
#define Debug(x...) _debug_print_format(#x, x);
#else
#define debug(x...)
#define Debug(x...)
#endif
template<typename...Args> void print_(Args...args){((cout<<args<<" "),...)<<endl;}
#define rep(i,a,b) for(int i=(a);i<(int)(b);++i)
#define sz(v) ((int)(v).size())
#define print(...) print_(__VA_ARGS__);
#define FIND(a, x) ((find(a.begin(),a.end(),(x))!=a.end())?1:0)
#define cmin(x,...) x=min({(x), __VA_ARGS__})
#define cmax(x,...) x=max({(x), __VA_ARGS__})
#define INTMAX (int)(9223372036854775807)
#define INF (int)(1152921504606846976)
#define double long double
#define int long long
#define MAXN 200010



struct graph {
    struct node {
        int v, w;
        bool operator<(const node &other) const {
            return w < other.w;
        }
        bool operator==(const node &other) const {
            return v == other.v && w == other.w;
        }
    };
    vector<vector<node>> e;
    int n;
    bool directed;
    graph(int V, bool D = 0) {
        n = V;
        e.resize(n);
        directed = D;
    }
    void add_edge(int u, int v, int w = 1) {
        e[u].push_back(node{v, w});
    }
    int kruskal() {
        struct DSU {
            vector<int> parent, rank;
            DSU(int n) {
                parent.resize(n);
                rank.resize(n);
                rep(i, 0, n) parent[i] = i;
            }
            int find(int x) {
                if (parent[x] != x) parent[x] = find(parent[x]);
                return parent[x];
            }
            void unite(int x, int y) {
                int rx = find(x), ry = find(y);
                if (rx == ry) return;
                if (rank[rx] < rank[ry]) parent[rx] = ry;
                else if (rank[rx] > rank[ry]) parent[ry] = rx;
                else parent[ry] = rx, ++rank[rx];
            }
        };
        vector<pair<int, pair<int, int>>> edges;
        rep(u, 0, n) {
            for (auto [v, w]: e[u]) {
                edges.push_back({w, {u, v}});
            }
        }
        sort(edges.begin(), edges.end());
        int ans = 0, cnt = 0;
        DSU dsu(n);
        for (auto [w, p]: edges) {
            auto [u, v] = p;
            if (dsu.find(u) == dsu.find(v)) continue;
            dsu.unite(u, v);
            ans += w;
            if (++cnt == n-1) break;
        }
        return (cnt==n-1 ? ans : INF);
    }
    void graphviz_dump(string filename = "graph.dot") {
        ofstream gf; gf.open(filename);
        gf << (directed ? "digraph" : "graph") << " {\n";
        gf << "    "; rep(i, 0, n) gf << i << " ;"[i==n-1]; gf << endl;
        string notation = directed ? " -> " : " -- ";
        bool weighted = 0;
        for (auto es: e) for (auto edge: es) if (edge.w != 1) weighted = 1;
        rep(u, 0, n) {
            for (auto [v, w]: e[u]) {
                if (!directed && u > v) continue;
                gf << "    " << u << notation << v << (weighted ? " ;\n" : ";\n");
            }
        }
        gf << "}\n";
    }
};


int32_t main() {
    ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);

    int n, m; cin >> n >> m;
    graph g(n);
    rep(i, 0, m) {
        int u, v, w; cin >> u >> v >> w;
        g.add_edge(u-1, v-1, w);
    }
    int ans = g.kruskal();
    if (ans == INF) cout << "IMPOSSIBLE\n";
    else cout << ans << endl;

    return 0;
}