#include <bits/stdc++.h>
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"

#define NDEBUG
using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
using uint = unsigned int;
using usize = std::size_t;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<typename T> constexpr T popcount(const T u) { return u ? static_cast<T>(__builtin_popcountll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T log2p1(const T u) { return u ? static_cast<T>(64 - __builtin_clzll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T msbp1(const T u) { return log2p1(u); }
template<typename T> constexpr T lsbp1(const T u) { return __builtin_ffsll(u); }
template<typename T> constexpr T clog(const T u) { return u ? log2p1(u - 1) : static_cast<T>(u); }
template<typename T> constexpr bool ispow2(const T u) { return u and (static_cast<u64>(u) & static_cast<u64>(u - 1)) == 0; }
template<typename T> constexpr T ceil2(const T u) { return static_cast<T>(1) << clog(u); }
template<typename T> constexpr T floor2(const T u) { return u == 0 ? static_cast<T>(0) : static_cast<T>(1) << (log2p1(u) - 1); }
template<typename T> constexpr bool btest(const T mask, const usize ind) { return ((static_cast<u64>(mask) >> ind) & static_cast<u64>(1)); }
template<typename T> constexpr T bcut(const T mask, const usize ind) { return ind == 0 ? static_cast<T>(0) : static_cast<T>((static_cast<u64>(mask) << (64 - ind)) >> (64 - ind)); }
template<typename T> bool chmin(T& a, const T& b) { return (a > b ? a = b, true : false); }
template<typename T> bool chmax(T& a, const T& b) { return (a < b ? a = b, true : false); }
constexpr unsigned int mod                  = 1000000007;
template<typename T> constexpr T inf_v      = std::numeric_limits<T>::max() / 4;
template<typename Real> constexpr Real pi_v = Real{3.141592653589793238462643383279502884};
template<typename T>
T read()
{
    T v;
    return std::cin >> v, v;
}
template<typename T>
std::vector<T> read_vec(const std::size_t size)
{
    std::vector<T> v(size);
    for (auto& e : v) { std::cin >> e; }
    return v;
}
template<typename... Types>
auto read_vals() { return std::tuple<std::decay_t<Types>...>{read<Types>()...}; }
#define SHOW(...) static_cast<void>(0)
template<typename T>
std::vector<T> make_v(const std::size_t size, T v) { return std::vector<T>(size, v); }
template<class... Args>
auto make_v(const std::size_t size, Args... args) { return std::vector<decltype(make_v(args...))>(size, make_v(args...)); }

class unionfind
{
public:
    unionfind(const usize sz) : sz{sz}, rt(sz), comp_sz(sz, 1) { std::iota(rt.begin(), rt.end(), 0); }
    usize root(const usize a) { return assert(a < sz), rt[a] == a ? a : rt[a] = root(rt[a]); }
    bool same(const usize a, const usize b) { return assert(a < sz), assert(b < sz), root(a) == root(b); }
    bool unite(usize a, usize b)
    {
        assert(a < sz), assert(b < sz), a = root(a), b = root(b);
        if (a == b) { return false; }
        if (comp_sz[a] < comp_sz[b]) { std::swap(a, b); }
        return comp_sz[a] += comp_sz[b], rt[b] = a, true;
    }
    usize size() const { return sz; }
    usize size_of(const usize a) { return assert(a < sz), comp_sz[root(a)]; }
    friend std::ostream& operator<<(std::ostream& os, const unionfind& uf)
    {
        os << "[";
        for (usize i = 0; i < uf.sz; i++) { os << uf.rt[i] << (i + 1 == uf.sz ? "" : ","); }
        return (os << "]\n");
    }

private:
    const usize sz;
    std::vector<usize> rt, comp_sz;
};
int main()
{
    const auto n = read<usize>();
    const auto m = read<ll>();
    const auto q = read<usize>();
    unionfind uf(n);
    std::vector<usize> a(q), b(q), c(q);
    ll cn = n;
    for (usize i = 0; i < q; i++) {
        std::cin >> a[i] >> b[i] >> c[i];
        if (c[i] == 0) {
            if (uf.unite(a[i], b[i])) { cn--; }
        }
    }
    for (usize i = 0; i < q; i++) {
        if (c[i] == 1 and (uf.same(a[i], b[i]) or cn <= 2 or m == n - 1)) { return std::cout << "No" << std::endl, 0; }
    }
    const ll max = (ll)n - cn + (cn - 1) * cn / 2;
    std::cout << (m <= max ? "Yes" : "No") << std::endl;
    return 0;
}


Measured memory_bytes: 4224