/* Problem URL: https://cses.fi/problemset/task/1675 */

#include <bits/stdc++.h>

using namespace std;

#define V vector

#define rmin(a, b) a = min(a, b)
#define rmax(a, b) a = max(a, b)

#define rep(i, lim) for (size_t i = 0; i < (lim); i++)
#define nrep(i, s, lim) for (size_t i = s; i < (lim); i++)

#define repv(i, v) for (auto &i : (v))
#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
#define sortv(v) sort(v.begin(), v.end())
#define all(v) (v).begin(), (v).end()

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;

using ll = long long;

using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vvvvl = vector<vvvl>;

template<class v>
auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
    os << vec[0];
    for (size_t i = 1; i < vec.size(); i++) {
        os << ' ' << vec[i];
    }
    os << '\n';
    return os;
}

template<class v>
auto operator>>(istream &is, vector<v> &vec)->istream& {
    for (auto &i : vec) {
        is >> i;
    }
    return is;
}

template<class v>
auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
    for (auto &i : vec) {
        os << i[0];
        for (size_t j = 1; j < i.size(); j++) {
            os << ' ' << i[j];
        }
        os << '\n';
    }
    return os;
}

template<class v>
auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
    for (auto &i : vec) {
        for (auto &j : i) {
            is >> j;
        }
    }
    return is;
}

vi dsu;
ll cost;
int c;

int find_p(int i)
{
    if (i == dsu[i]) {
        return i;
    }
    return dsu[i] = find_p(dsu[i]);
}

void make_pair(int a, int b, ll v)
{
    a = find_p(a);
    b = find_p(b);

    if (a == b) {
        return;
    }

    cost += v;
    c--;

    dsu[b] = a;
}

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

    int n, m;
    cin >> n >> m;

    dsu.resize(n);
    rep(i, n) {
        dsu[i] = i;
    }
    c = n;

    V<tuple<ll, int, int>> edges(m);
    for (auto &[v, x, y] : edges) {
        cin >> x >> y >> v;
        x--, y--;
    }

    sortv(edges);

    for (auto &[v, x, y] : edges) {
        make_pair(x, y, v);
    }

    if (c != 1) {
        cout << "IMPOSSIBLE\n";
        return 0;
    }

    cout << cost << '\n';
}