#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template <class T> using treap = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define int long long
#define REP(i, n) for (long long i = 0, max_i = (n); i < max_i; i++)
#define REPI(i, a, b) for (long long i = (a), max_i = (b); i < max_i; i++)
#define ALL(obj) begin(obj), end(obj)
#define RALL(obj) rbegin(obj), rend(obj)
#define fi first
#define se second
using ii = pair<int, int>;
vector<ii> dirs = {
    {1, 0}, {0, 1}, {-1, 0}, {0, -1},  // 4方向
    {1, 1}, {-1, 1}, {-1, -1}, {1, -1},  // 斜め
    {0, 0},  // 自身
};
template <class T> inline bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } return false; }
template <class T> inline bool chmin(T& a, const T& b) { if (a > b) { a = b; return true; } return false; }
template <class T, class S> vector<T> make_vec(size_t n, S x) { return vector<T>(n, x); }
template <class T, class... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec<T>(ts...))>(n, make_vec<T>(ts...)); }

// debug
template <class T> ostream& operator<<(ostream& s, vector<T>& d) { REP (i, d.size()) s << d[i] << (i == d.size() - 1 ? "" : " "); return s; }
template <class T> ostream& operator<<(ostream& s, vector<vector<T>>& d) { REP (i, d.size()) s << d[i] << (i == d.size() - 1 ? "" : "\n"); return s; }
template <class T, class S> ostream& operator<<(ostream& s, pair<T, S>& p) { s << "{" << p.first << ", " << p.second << "}"; return s; }
template <class T> ostream& operator<<(ostream& s, set<T> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
template <class T> ostream& operator<<(ostream& s, multiset<T> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
template <class T, class S> ostream& operator<<(ostream& s, map<T, S> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
template <class T, class S> ostream& operator<<(ostream& s, unordered_map<T, S> m) { for (auto it = m.begin(); it != m.end(); it++) { s << *it << (next(it) == m.end() ? "" : "\n"); } return s; }
#ifdef _MY_DEBUG
    #define dump(...) cerr << "/* " << #__VA_ARGS__ << " :[" << __LINE__ << ":" << __FUNCTION__ << "]" << endl, dump_func(__VA_ARGS__), cerr << "*/\n\n";
#else
    #define dump(...)
    #define endl "\n"
#endif
void dump_func() { cerr << endl; }
template <class Head, class... Tail> void dump_func(Head&& h, Tail&&... t) { cerr << h << (sizeof...(Tail) == 0 ? "" : ", "), dump_func(forward<Tail>(t)...); }

struct Fast { Fast() { cin.tie(nullptr); ios::sync_with_stdio(false); } } fast;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
constexpr int MOD = 1000000007;
// *************** TEMPLATE END *************** 

struct UnionFind {
    int cnt;                   // 集合の数
    vector<int> number;        // 0以上のとき親のindex, 負のときは集合サイズ
    vector<int> data1, data2;  // 連結成分ごとのデータ
    UnionFind(int n) : cnt(n), number(n, -1) {}
    UnionFind(const vector<int>& data1, const vector<int>& data2)
        : cnt(data1.size()), number(data1.size(), -1), data1(data1), data2(data2) {}
    int root(int x) { return number[x] < 0 ? x : number[x] = root(number[x]); }
    void unite(int x, int y) {
        x = root(x);
        y = root(y);
        if (x == y) return;
        if (number[y] < number[x]) swap(x, y);
        // yをxにマージ
        number[x] += number[y];
        number[y] = x;
        // // dataのマージ方法に合わせて変える
        // data1[x] += data1[y];
        // data2[x] += data2[y];
        cnt--;
    }
    bool is_same(int x, int y) { return root(x) == root(y); }
    int size(int x) { return -number[root(x)]; }
    int& ref1(int x) { return data1[root(x)]; }
    int& ref2(int x) { return data2[root(x)]; }
};

signed main() {
    int n, m, Q; cin >> n >> m >> Q;
    vector<ii> ps;
    UnionFind uf(n);
    REP (i, Q) {
        int u, v, c; cin >> u >> v >> c;
        if (c == 0) {
            uf.unite(u, v);
        } else {
            ps.push_back({u, v});
        }
    }
    bool ng = false;
    for (auto& p : ps) {
        if (uf.is_same(p.fi, p.se)) ng = true;
    }
    int cnt = 0;
    REP (i, n) {
        if (uf.size(i) == 1) cnt++;
    }
    if (cnt == 0 && ps.size() != 0) ng = true;

    int e = uf.cnt - 1;
    REP (i, n) {
        if (uf.root(i) == i) e += uf.size(i) - 1;
    }
    int mi = e;
    if (ps.size()) mi++;
    if (m < mi) ng = true;

    int ma = e;
    ma += uf.cnt * (uf.cnt - 1) / 2 - (uf.cnt - 1);
    if (m > ma) ng = true;

    cout << (ng ? "No" : "Yes") << endl;
}


Measured memory_bytes: 3188