#if __has_include("../library/Basic/Debug.hpp")

#include "../library/Basic/Debug.hpp"

#else

/* ----- Header Files ----- */
// IO
#include <cstdio>
#include <iomanip>
#include <ios>
#include <iostream>

// algorithm
#include <algorithm>
#include <cmath>
#include <numeric>

// container
#include <vector>
#include <array>
#include <string>
#include <tuple>
#include <complex>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <bitset>

// others
#include <random>
#include <limits>
#include <functional>
#include <ctime>
#include <cassert>
#include <cstdint>

/* ----- Type Alias ----- */
using Int = long long int;
using Real = long double;
using std::array;
using std::pair;
using std::string;
using std::tuple;
using std::vector;
template <class T>
using MaxHeap = std::priority_queue<T>;
template <class T>
using MinHeap = std::priority_queue<T, std::vector<T>, std::greater<T>>;

template <class T>
T genv(T v) { return v; }

template <class T, class... Ts>
auto genv(size_t l, Ts... ts) {
    return vector<decltype(genv<T>(ts...))>(l, genv<T>(ts...));
}

template <class Cost = Int>
struct Edge {
    Int src, dst;
    Cost cost;
    Edge(Int src = -1, Int dst = -1, Cost cost = 1)
        : src(src), dst(dst), cost(cost){};

    bool operator<(const Edge<Cost>& e) const { return this->cost < e.cost; }
    bool operator>(const Edge<Cost>& e) const { return this->cost > e.cost; }
};

template <class Cost = Int>
using Edges = vector<Edge<Cost>>;
template <class Cost = Int>
using Graph = vector<vector<Edge<Cost>>>;

#endif

struct UnionFind {
    vector<int> par, num;
    int gnum;

    UnionFind(int N) : par(N), num(N, 1), gnum(N) {
        iota(par.begin(), par.end(), 0);
    }

    int find(int v) {
        return (par[v] == v) ? v : (par[v] = find(par[v]));
    }

    void unite(int u, int v) {
        u = find(u), v = find(v);
        if (u == v) return;

        if (num[u] < num[v]) std::swap(u, v);
        num[u] += num[v];
        par[v] = u;
        --gnum;
    }

    bool same(int u, int v) { return find(u) == find(v); }
    bool ispar(int v) { return v == find(v); }
    int size(int v) { return num[find(v)]; }
};

/* ----- Misc ----- */
void fastio() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
}

struct Fout {
    Int precision;
    Fout(Int precision) : precision(precision) {}
};
std::ostream& operator<<(std::ostream& os, const Fout& fio) {
    os << std::fixed << std::setprecision(fio.precision);
    return os;
}


/* ----- Constants ----- */
// constexpr Int INF = std::numeric_limits<Int>::max() / 3;
// constexpr Int MOD = 1000000007;
// const Real PI = acos(-1);
// constexpr Real EPS = 1e-10;
// std::mt19937 mt(int(std::time(nullptr)));

void fail() {
    std::cout << "No" << std::endl;
    std::exit(0);
}

int main() {
    Int n, m;
    int q;
    std::cin >> n >> m >> q;

    Edges<> single, mult;
    for (int i = 0; i < q; ++i) {
        int u, v, c;
        std::cin >> u >> v >> c;
        if (c == 0) {
            single.emplace_back(u, v);
        } else {
            mult.emplace_back(u, v);
        }
    }

    UnionFind uf(n);
    for (auto e : single) {
        uf.unite(e.src, e.dst);
    }
    for (auto e : mult) {
        if (uf.same(e.src, e.dst)) fail();
    }

    std::set<int> pars;
    for (int v = 0; v < n; ++v) {
        pars.insert(uf.find(v));
    }
    Int k = pars.size();

    if (k <= 2 && !mult.empty()) fail();
    if (m == n - 1 && !mult.empty()) fail();

    Int upper = (n - k) + k * (k - 1) / 2;
    if (m > upper) fail();

    std::cout << "Yes" << std::endl;
    return 0;
}


Measured memory_bytes: 8304