#include <bits/stdc++.h>
using namespace std;
typedef bool boolean;

const int N = 1e5 + 5;

#define pii pair<int, int>
#define ll long long

int n, q;
ll m;
int uf[N];
vector<pii> E0, E1;

int find(int x) {
	return uf[x] == x ? x : uf[x] = find(uf[x]);
}
boolean unit(int x, int y) {
	x = find(x), y = find(y);
	if (x ^ y) {
		uf[x] = y;
		return true;
	}
	return false;
}

void quitf(boolean expression) {
	if (expression) {
		puts("No");
		exit(0);
	}
}

int main() {
	scanf("%d%lld%d", &n, &m, &q);
	for (int i = 1; i <= n; i++)
		uf[i] = i;
	for (int i = 1, u, v, opt; i <= q; i++) {
		scanf("%d%d%d", &u, &v, &opt);
		++u, ++v;
		if (opt == 0) {
			E0.emplace_back(u, v);
		} else {
			E1.emplace_back(v, u);
		}
	}
	for (auto e : E0)
		unit(e.first, e.second);
	for (auto e : E1)
		quitf(find(e.first) == find(e.second));
	int comp = 0;
	for (int i = 1; i <= n; i++)
		comp += find(i) == i;
	quitf(E1.size() && comp == 2);
	ll mi = ((E1.size()) ? (n) : (n - 1));
	ll mx = (n - comp) + (comp * 1ll * (comp - 1) >> 1);
	quitf(m < mi || m > mx);
	puts("Yes");
	return 0;
}
