#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace std;
using ll=long long;
using datas=pair<ll,ll>;
using tdata=pair<ll,datas>;
using vec=vector<ll>;
using mat=vector<vec>;
using pvec=vector<datas>;
using pmat=vector<pvec>;
#define For(i,a,b) for(i=a;i<b;i++)
#define bFor(i,a,b) for(i=a;i>=b;i--)
#define rep(i,N) For(i,0,N)
#define rep1(i,N) For(i,1,N)
#define brep(i,N) bFor(i,N-1,0)
#define all(v) (v).begin(),(v).end()
#define allr(v) (v).rbegin(),(v).rend()
#define vsort(v) sort(all(v))
#define vrsort(v) sort(allr(v))
#define mod 1000000007
#define endl "\n"
#define output(v) do{bool f=0;for(auto i:v){cout<<(f?" ":"")<<i;f=1;}cout<<endl;}while(0)

long mmid(long a,long b,long c){return a<b?(b<c?b:max(a,c)):(b>c?b:min(a,c));}

ll modinv(ll a) {
  ll b=mod,u=1,v=0,t;
  while(b){
    t=a/b;
    a-=t*b; swap(a,b);
    u-=t*v; swap(u,v);
  }
  return (u+mod)%mod;
}

ll moddevide(ll a,ll b){return (a*modinv(b))%mod;}

ll modncr(ll n,ll r){
  ll i,plus=1;
  rep(i,r){
    plus=(plus*(n-i))%mod;
    plus=moddevide(plus,i+1);
  }
  return plus;
}

ll modncrlistp[200000],modncrlistm[200000];

ll modncrs(ll n,ll r){
  ll i,j;
  if(modncrlistp[n]==0){
    for(i=n;i>=0;i--){
      if(modncrlistp[i])break;
    }
    if(i<0){
      modncrlistp[0]=1;
      rep1(i,n+1){
        modncrlistp[i]=(modncrlistp[i-1]*i)%mod;
      }
    }else{
      For(j,i+1,n+1){
        modncrlistp[j]=(modncrlistp[j-1]*j)%mod;
      }
    }
  }
  if(modncrlistm[n]==0){
    for(i=n;i>=0;i--){
      if(modncrlistm[i])break;
    }
    if(i<0){
      modncrlistm[0]=1;
      rep1(i,n+1){
        modncrlistm[i]=(modncrlistm[i-1]*modinv(i))%mod;
      }
    }else{
      For(j,i+1,n+1)modncrlistm[j]=(modncrlistm[j-1]*modinv(j))%mod;
    }
  }
  return (((modncrlistp[n]*modncrlistm[r])%mod)*modncrlistm[n-r])%mod;
}

ll gcd(ll a,ll b){if(!b)return a;return (a%b==0)?b:gcd(b,a%b);}

ll countdigits(ll n){
  ll ans=0;
  while(n){n/=10;ans++;}
  return ans;
}

ll sumdigits(ll n){
  ll ans=0;
  while(n){ans+=n%10;n/=10;}
  return ans;
}

vec eratosthenes(ll N){
  ll i;
  vec ch(N+1,1),p;
  ch[0]=ch[1]=0;
  rep(i,N+1){
    if(ch[i]){
      p.push_back(i);
      for(ll j=2;i*j<=N;j++){
        ch[i*j]=0;
      }
    }
  }
  return ch;
}

struct unionfind{
  vec par,treesize;
  unionfind(ll N) :par(N){
    ll i;
    rep(i,N)par[i]=i;
    treesize.resize(N);
    rep(i,N)treesize[i]=1;
  }
  ll root(ll x){
    ll r;
    if(par[x]==x)return x;
    r=root(par[x]);
    if(par[x]!=r){
      treesize[r]+=treesize[x];
      treesize[x]=0;
      par[x]=r;
    }
    return r;
  }
  void unite(ll x,ll y){
    ll px=root(x);
    ll py=root(y);
    if(px!=py){
      par[px]=py;
      treesize[py]+=treesize[px];
      treesize[px]=0;
    }
  }
  bool parcheck(ll x,ll y){
    ll px=root(x);
    ll py=root(y);
    return px==py;
  }
  ll size(ll x){
    ll px=root(x);
    return treesize[px];
  }
  void clear(){
    ll i;
    rep(i,(ll)par.size()){
      par[i]=i;
      treesize[i]=1;
    }
  }
};

int main(){
  ll i,N,M,Q,a,b,c,K;
  cin>>N>>M>>Q;
  unionfind tree(N);
  pvec v;
  rep(i,Q){
    cin>>a>>b>>c;
    if(c){
      v.push_back(datas(a,b));
    }else{
      tree.unite(a,b);
    }
  }
  set<ll> se;
  rep(i,N){
    se.insert(tree.root(i));
  }

  K=se.size();
  if(K<3){
    if(M==N-1&&v.size()==0){
      cout<<"Yes"<<endl;
    }else{
      cout<<"No"<<endl;
    }
  }else{
    for(auto i:v){
      if(tree.parcheck(i.first,i.second)){
        cout<<"No"<<endl;
        return 0;
      }
    }
    if(M<=K*(K-1)/2+(N-K)){
      if(v.size()==0)M++;
      if(N<=M){
        cout<<"Yes"<<endl;
        return 0;
      }
    }
    cout<<"No"<<endl;
  }
  return 0;
}

Measured memory_bytes: 8560