#include <iostream>
#include <cstring>
#include <algorithm>
#include <vector>
#include <string>
#include <math.h>
#include <iomanip>
#include <limits>
#include <list>
#include <queue>
#include <tuple>
#include <map>
#include <stack>
#include <set>
using namespace std;
#define MOD (long long int)(998244353)
#define ll long long int
#define rep(i,n) for(int i=0; i<(int)(n); i++)
#define reps(i,n) for(int i=1; i<=(int)(n); i++)
#define REP(i,n) for(int i=n-1; i>=0; i--)
#define REPS(i,n) for(int i=n; i>0; i--)
#define INF (int)(1123456789)
#define LINF (long long int)(112345678901234567)
#define chmax(a, b) a = (((a)<(b)) ? (b) : (a))
#define chmin(a, b) a = (((a)>(b)) ? (b) : (a))
#define all(v) v.begin(), v.end()

const int N = (int)3e5;

ll mpow(ll a, ll b){
  if(b==0) return 1;
  else if(b%2==0){ll memo = mpow(a,b/2); return memo*memo%MOD;}
  else return mpow(a,b-1) * a % MOD;
}
ll lpow(ll a, ll b){
  if(b==0) return 1;
  else if(b%2==0){ll memo = lpow(a,b/2); return memo*memo;}
  else return lpow(a,b-1) * a;
}
ll gcd(ll a, ll b){
  if(b==0) return a;
  else return gcd(b, a%b);
}
vector<ll> kaijo_memo;
ll kaijo(ll n){
  if(kaijo_memo.size() > n) return kaijo_memo[n];
  if(kaijo_memo.size() == 0) kaijo_memo.push_back(1);
  while(kaijo_memo.size() <= n) kaijo_memo.push_back(kaijo_memo[kaijo_memo.size()-1] * kaijo_memo.size() % MOD);
  return kaijo_memo[n];
}
vector<ll> gyaku_kaijo_memo;
ll gyaku_kaijo(ll n){
  if(gyaku_kaijo_memo.size() > n) return gyaku_kaijo_memo[n];
  if(gyaku_kaijo_memo.size() == 0) gyaku_kaijo_memo.push_back(1);
  while(gyaku_kaijo_memo.size() <= n) gyaku_kaijo_memo.push_back(gyaku_kaijo_memo[gyaku_kaijo_memo.size()-1] * mpow(gyaku_kaijo_memo.size(), MOD-2) % MOD);
  return gyaku_kaijo_memo[n];
}

ll nCr(ll n, ll r){
  if(n == r) return 1;//0個の丸と-1個の棒みたいな時に時に効く？不安.
  if(n < r || r < 0) return 0;
  ll ret = 1;
  ret *= kaijo(n); ret %= MOD;
  ret *= gyaku_kaijo(r); ret %= MOD;
  ret *= gyaku_kaijo(n-r); ret %= MOD;
  return ret;
}

vector<int> p,size;
int remain;

int find(int a){
  if(p[a] == a){
    return a;
  }else{
    return p[a] = find(p[a]);
  }
}

void unite(int a, int b){
  int pa = find(a); int pb = find(b);
  if(find(a) == find(b)){
    return;
  }
  p[pa] = pb;

}


int main(void){
  ll n,m,q;cin>>n>>m>>q;
  vector<pair<ll,ll>> E0,E1;
  rep(i,n){
    p.push_back(i);
    size.push_back(1);
  }
  rep(i,q){
    ll a,b,c;
    cin>>a>>b>>c;
    if(c==0){
      E0.push_back({a,b});
    }else{
      E1.push_back({a,b});
    }
  }
  rep(i,E0.size()){
    if(find(E0[i].first) != find(E0[i].second)){
      m--;
    }
    unite(E0[i].first, E0[i].second);
  }

  rep(i,E1.size()){
    if(find(E1[i].first) == find(E1[i].second)){
      cout<<"No"<<endl;
      return 0;
    }
  }
  vector<bool> kouho;
  rep(i,n){
    kouho.push_back(false);
  }
  int count = 0;
  rep(i,n){
    int pa = find(i);
    if(!kouho[pa]){
      kouho[pa] = true;
      count++;
    }
  }
  if(count <= 2 && E1.size() > 0){
    cout<<"No"<<endl;
    return 0;
  }
  ll k = count;

  if(E1.size() == 0){
    if(k-1 <= m && m <= k*(k-1)/2){
      cout<<"Yes"<<endl;
    }else{
      cout<<"No"<<endl;
    }
  }else{
    if(k <= m && m <= k*(k-1)/2){
      cout<<"Yes"<<endl;
    }else{
      cout<<"No"<<endl;
    }
  }

  return 0;
}


Measured memory_bytes: 4208