#include <cstdio>
#include <vector>
#include <algorithm>
using namespace std;

typedef long long ll;
const int Maxn = 1e5;

int N, K;
ll M;
vector<pair<int, int> > t;

int fa[Maxn + 5];
int find(int x) {
	if(x == fa[x]) return x;
	return fa[x] = find(fa[x]);
}

int main() {
#ifdef LOACL
	freopen("in.txt", "r", stdin);
	freopen("out.txt", "w", stdout);
#endif
	scanf("%d %lld %d", &N, &M, &K);
	for(int i = 1; i <= N; i++)
		fa[i] = i;
	for(int i = 1; i <= K; i++) {
		int u, v, typ;
		scanf("%d %d %d", &u, &v, &typ);
		u++, v++;
		if(typ == 0) {
			int fu = find(u), fv = find(v);
			if(fu != fv) fa[fu] = fv;
		} else t.push_back(make_pair(u, v));
	}
	int cnt = 0;
	for(int i = 1; i <= N; i++)
		if(i == find(i)) cnt++;
	ll mx = 1LL * cnt * (cnt - 1) / 2 + N - cnt;
	if(mx < M) {
		puts("No");
		return 0;
	}
	ll mn = (t.empty() ? N - 1 : N);
	if(mn > M) {
		puts("No");
		return 0;
	}
	for(int i = 0; i < (int)t.size(); i++)
		if(find(t[i].first) == find(t[i].second)) {
			puts("No");
			return 0;
		}
	puts("Yes");
	return 0;
}
