#include <algorithm>
#include <bitset>
#include <cmath>
#include <complex>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <regex>
#include <set>
#include <stack>
#include <string>
#include <vector>

const int MOD = 1e9 + 7;
const int iINF = 2147483647 / 2;
const long long int llINF = 9223372036854775807 / 2;

using namespace std;
using ll = long long int;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vvvl = vector<vector<vector<ll>>>;

typedef pair<ll, ll> pll;
bool paircomp(const pll &a, const pll &b) {
  if (a.first == b.first)
    return a.second < b.second;
  return a.first < b.first;
}

#define REP(i, n) for (ll i = 0; i < (n); i++)
#define RREP(i, n) for (ll i = (n)-1; i >= 0; i--)
#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define AUTO(i, m) for (auto &i : m)
#define ALL(a) (a).begin(), (a).end()
#define MAX(vec) *std::max_element(vec.begin(), vec.end())
#define MIN(vec) *std::min_element(vec.begin(), vec.end())
#define ARGMAX(vec)                                                            \
  std::distance(vec.begin(), std::max_element(vec.begin(), vec.end()))
#define ARGMIN(vec)                                                            \
  std::distance(vec.begin(), std::min_element(vec.begin(), vec.end()))
#define REV(T) greater<T>()
#define PQ(T) priority_queue<T, vector<T>, greater<T>>
#define VVL(a, b, c) vector<vector<ll>>(a, vector<ll>(b, c))
#define VVVL(a, b, c, d)                                                       \
  vector<vector<vector<ll>>>(a, vector<vector<ll>>(b, vector<ll>(c, d)))
#define SP(a) setprecision(a)
#define SQRT(a) sqrt((long double)(a))
#define DPOW(a, b) pow((long double)(a), (long double)(b))
#define UNIQUE(vec)                                                            \
  do {                                                                         \
    sort(ALL((vec)));                                                          \
    (vec).erase(std::unique(ALL((vec))), (vec).end());                         \
  } while (0)

ll POW(ll n, ll m) {
  if (m == 0) {
    return 1;
  } else if (m % 2 == 0) {
    ll tmp = POW(n, m / 2);
    return (tmp * tmp);
  } else {
    return (n * POW(n, m - 1));
  }
}

struct UnionFind {
  vector<ll> data;

  UnionFind(ll sz) { data.assign(sz, -1); }

  bool unite(ll x, ll y) {
    x = root(x), y = root(y);
    if (x == y)
      return (false);
    if (data[x] > data[y])
      swap(x, y);
    data[x] += data[y];
    data[y] = x;
    return (true);
  }

  ll root(ll k) {
    if (data[k] < 0)
      return (k);
    return (data[k] = root(data[k]));
  }

  ll size(ll k) { return (-data[root(k)]); }

  ll same(ll a, ll b) { return root(a) == root(b); }
};

int dx[4] = {1, 0, -1, 0};
int dy[4] = {0, 1, 0, -1};

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ll N, M, Q;
  cin >> N >> M >> Q;
  auto uf = UnionFind(N);
  vl A, B;
  REP(i, Q) {
    ll a, b, c;
    cin >> a >> b >> c;
    if (c == 1) {
      A.push_back(a);
      B.push_back(b);
    } else {
      uf.unite(a, b);
    }
  }
  set<ll> s;
  REP(i, N) { s.insert(uf.root(i)); }

  bool ok = true;
  REP(i, A.size()) {
    if (uf.same(A[i], B[i])) {
      ok = false;
      break;
    }
  }
  ll K = s.size();
  if (A.size() > 0 && (M == N - 1 || K <= 2))
    ok = false;
  if (N - K + (K * (K - 1) / 2) < M)
    ok = false;

  if (ok)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  return 0;
}


Measured memory_bytes: 7276