#include <bits/stdc++.h>
#ifdef LOCAL
#include <debug.hpp>
#else
#define debug(...) void(0)
#endif

template <class T> std::istream& operator>>(std::istream& is, std::vector<T>& v) {
    for (auto& x : v) is >> x;
    return is;
}

template <class T> std::ostream& operator<<(std::ostream& os, const std::vector<T>& v) {
    auto sep = "";
    for (const auto& x : v) os << std::exchange(sep, " ") << x;
    return os;
}

template <class T, class U = T> bool chmin(T& x, U&& y) { return y < x and (x = std::forward<U>(y), true); }

template <class T, class U = T> bool chmax(T& x, U&& y) { return x < y and (x = std::forward<U>(y), true); }

template <class T> void mkuni(std::vector<T>& v) {
    std::sort(begin(v), end(v));
    v.erase(unique(begin(v), end(v)), end(v));
}

template <class T> int lwb(const std::vector<T>& v, const T& x) {
    return std::lower_bound(begin(v), end(v), x) - begin(v);
}

template <typename T> struct DirectedShortestCycle {
    struct edge {
        int from, to;
        T cost;
        edge(int from, int to, T cost) : from(from), to(to), cost(cost) {}
    };

    std::vector<std::vector<int>> G;
    std::vector<edge> edges;

    DirectedShortestCycle(int n) : n(n), G(n) {}

    void add_edge(int u, int v, T w) {
        assert(0 <= u and u < n);
        assert(0 <= v and v < n);
        assert(w >= 0);
        G[u].emplace_back(edges.size());
        edges.emplace_back(u, v, w);
    }

    std::tuple<T, std::vector<int>, std::vector<int>> solve(int r) {
        std::vector<int> prve(n, -1);
        std::vector<T> dist(n, inf);
        std::priority_queue<std::pair<T, int>, std::vector<std::pair<T, int>>, std::greater<>> pq;
        for (const int& idx : G[r]) {
            int u = edges[idx].to, w = edges[idx].cost;
            if (w < dist[u]) {
                dist[u] = w;
                prve[u] = idx;
                pq.emplace(dist[u], u);
            }
        }
        while (not pq.empty()) {
            auto [d, v] = pq.top();
            pq.pop();
            if (dist[v] < d) continue;
            for (const int& idx : G[v]) {
                int u = edges[idx].to, w = edges[idx].cost;
                if (dist[u] <= dist[v] + w) continue;
                dist[u] = dist[v] + w;
                prve[u] = idx;
                pq.emplace(dist[u], u);
            }
        }

        if (dist[r] == inf) return {inf, {}, {}};
        std::vector<int> vs, es;
        vs.emplace_back(r);
        while (true) {
            int idx = prve[vs.back()];
            es.emplace_back(idx);
            vs.emplace_back(edges[idx].from);
            if (vs.back() == r) break;
        }
        std::reverse(vs.begin(), vs.end());
        std::reverse(es.begin(), es.end());
        vs.pop_back();
        return {dist[r], vs, es};
    }

  private:
    constexpr static T inf = std::numeric_limits<T>::max() / 2;
    int n;
};

template <typename T> struct UndirectedShortestCycle {
    struct edge {
        int from, to;
        T cost;
        edge(int from, int to, T cost) : from(from), to(to), cost(cost) {}
    };

    std::vector<std::vector<int>> G;
    std::vector<edge> edges;

    UndirectedShortestCycle(int n) : n(n), G(n) {}

    void add_edge(int u, int v, T w) {
        assert(0 <= u and u < n);
        assert(0 <= v and v < n);
        assert(w >= 0);
        G[u].emplace_back(edges.size());
        G[v].emplace_back(edges.size());
        edges.emplace_back(u, v, w);
    }

    std::tuple<T, std::vector<int>, std::vector<int>> solve(int r) {
        std::vector<int> label(n, -1), prve(n, -1);
        std::vector<T> dist(n, inf);
        std::priority_queue<std::pair<T, int>, std::vector<std::pair<T, int>>, std::greater<>> pq;
        dist[r] = 0;
        pq.emplace(dist[r], r);
        label[r] = r;
        while (not pq.empty()) {
            auto [d, v] = pq.top();
            pq.pop();
            if (dist[v] < d) continue;
            for (const int& idx : G[v]) {
                int u = edges[idx].from ^ edges[idx].to ^ v, w = edges[idx].cost;
                if (dist[u] <= dist[v] + w) continue;
                dist[u] = dist[v] + w;
                label[u] = label[v] == r ? u : label[v];
                prve[u] = idx;
                pq.emplace(dist[u], u);
            }
        }

        std::vector<bool> used(edges.size(), false);
        for (int& idx : prve) {
            if (idx != -1) {
                used[idx] = true;
            }
        }
        T mini = inf;
        int argmin = -1;
        for (int i = 0; i < int(edges.size()); i++) {
            if (used[i]) continue;
            auto [u, v, w] = edges[i];
            if (label[u] == -1) continue;
            if (label[u] == label[v]) continue;
            if (dist[u] + dist[v] + w < mini) {
                mini = dist[u] + dist[v] + w;
                argmin = i;
            }
        }
        if (argmin == -1) return {mini, {}, {}};

        std::vector<int> vs, es;
        int a = edges[argmin].from, b = edges[argmin].to;
        while (a != r) {
            int idx = prve[a];
            vs.emplace_back(a);
            es.emplace_back(idx);
            a = edges[idx].from ^ edges[idx].to ^ a;
        }
        vs.emplace_back(a);
        std::reverse(vs.begin(), vs.end());
        std::reverse(es.begin(), es.end());
        es.emplace_back(argmin);
        while (b != r) {
            int idx = prve[b];
            vs.emplace_back(b);
            es.emplace_back(idx);
            b = edges[idx].from ^ edges[idx].to ^ b;
        }
        return {mini, vs, es};
    }

  private:
    constexpr static T inf = std::numeric_limits<T>::max() / 2;
    int n;
};

constexpr int INF = (1 << 30) - 1;
constexpr long long IINF = (1LL << 60) - 1;
constexpr int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};

typedef long long ll;
#define all(x) begin(x), end(x)

using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T;
    cin >> T;
    int N, M;
    cin >> N >> M;
    ll ans = IINF;
    if (T == 0) {
        UndirectedShortestCycle<long long> G(N);
        for (; M--;) {
            int u, v, w;
            cin >> u >> v >> w;
            G.add_edge(--u, --v, w);
        }
        for (int i = 0; i < N; i++) ans = min(ans, get<0>(G.solve(i)));
    } else {
        DirectedShortestCycle<long long> G(N);
        for (; M--;) {
            int u, v, w;
            cin >> u >> v >> w;
            G.add_edge(--u, --v, w);
        }
        for (int i = 0; i < N; i++) ans = min(ans, get<0>(G.solve(i)));
    }

    cout << (ans == IINF ? -1 : ans) << '\n';
    return 0;
}