#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
#ifdef _debug
#define dout(i) cout << #i << ' ' << i << ' '
#else 
#define dout(i) //
#endif
using ll = long long;
using ull = unsigned long long;
using ul = unsigned;
using db = double;
int n, q;
ll m, c;
vector<pair<int,int>> edge[2];
const int maxn = 100001;
int s[maxn], b[maxn];
string res[2] = {"No\n", "Yes\n"};
int find(int i){
	return i == b[i] ? i : b[i] = find(b[i]);
}
void merge(int x, int y){
	x = find(x), y = find(y);
	if(s[x] < s[y])swap(x, y);
	if(x != y){
		s[x] += s[y];
		b[y] = b[x];
		--c;
	}
}
#define same(a, b) (find(a) == find(b))
signed main(){
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> n >> m >> q;
	for(int i = 0, a, b, c;i < q;++i){
		cin >> a >> b >> c;
		edge[c].emplace_back(a, b);
	}
	if(m == n-1)return cout << res[edge[1].empty()], 0;
	c = n;
	for(int i = 1;i <= n;++i)b[i] = i, s[i] = 1;
	for(auto &p : edge[0])merge(p.first, p.second);
	for(auto &p : edge[1])if(same(p.first, p.second))return cout << res[0] , 0;
	cout << res[m <= n-c + c*(c-1)/2];
}