#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef pair<ll,ll> P;
 
long long int INF = 3e18;
double Pi = 3.1415926535897932384626;
 
vector<ll> G[550010];
//vector<P> tree[500010];
priority_queue <ll> pql;
priority_queue <P> pqp;
//big priority queue
priority_queue <ll,vector<ll>,greater<ll> > pqls;
priority_queue <P,vector<P>,greater<P> > pqps;
//small priority queue
//top pop
 
int dx[8]={1,0,-1,0,1,1,-1,-1};
int dy[8]={0,1,0,-1,1,-1,-1,1};
char dir[] = "DRUL";
//ll bit[500005];
//↓,→,↑,←
 
 
#define p(x) cout<<x<<"\n";
#define el cout<<endl;
#define pe(x) cout<<(x)<<" ";
#define ps(x) cout<<fixed<<setprecision(25)<<x<<endl;
#define pu(x) cout<<(x);
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define CLEAR(a) a = decltype(a)(); 
 
 
ll mod = 998244353;

ll rui(ll number1,ll number2){

    if(number2 == 0){
        return 1;
    }else{
        ll number3 = rui(number1,number2 / 2);
        number3 *= number3;
        number3 %= mod;
        if(number2%2==1){
            number3 *= number1;
            number3 %= mod;
        }
        return number3;
    }
}
ll gcd(ll number1,ll number2){
 
    if(number1 > number2){
        swap(number1,number2);
    }
    if(number1 == 0 || number1 == number2){
        return number2;
    }else{
        return gcd(number2 % number1,number1);
    }
}
void YES(bool condition){
 
    if(condition){
        p("YES");
    }else{
        p("NO");
    }
    return;
}
void Yes(bool condition){
 
    if(condition){
        p("Yes");
    }else{
        p("No");
    }
    return;
}

/*
ll fact[800005],rfact[800005];

void c3_init(){
    fact[0] = rfact[0] = 1;
    for(ll i=1; i<=800000; i++){
        fact[i] = (fact[i-1]*i) % mod;
    }
    rfact[800000] = rui(fact[800000],mod - 2);
    for(ll i=800000; i>=1; i--){
       rfact[i-1] = rfact[i] * i;
       rfact[i-1] %= mod;
    }
    return;}
ll c3(ll n,ll r){
    return (((fact[n] * rfact[r]) % mod ) * rfact[n-r]) % mod;}
*/
 
ll n,m,num,sum,a,b,c,d,e,g,h,w,i,j,q,r,l;
ll k,ans;
ll x[500005],y[500005],z[500005];
ll dp[1000005];
ll ans_table[1000005];
ll size[100005];
char s[500005];
bool dame = false;

ll p[500005],ran[500005];

//木の根っこを求める
ll find(ll x){
    if(p[x]==x){
        return x;
    }else{
        return p[x] = find(p[x]);
    }
}

//ｘとｙの属する集合を併合
void unite(ll x,ll y){
    x = find(x);
    y = find(y);
    if(x==y)return;
    if(ran[x]<ran[y]){
        p[x]=y;
    }else{
        p[y]=x;
        if(ran[x]==ran[y])ran[x]++;
    }
}

bool same(ll x,ll y){
    bool ok = false;
    if(find(x) == find(y)){
        ok = true;
    }
    return ok;
}

int main(){
    bool one = false;
    cin >> n >> m >> q;
    for(i=1;i<=3 * n;i++){
        p[i]=i;
    }
    for(int i=0;i<q;i++){
        cin >> a >> b >> c;
        if(c == 1){
            one = true;
        }
        x[i] = a;
        y[i] = b;
        z[i] = c;
    }
    for(int i=0;i<q;i++){
        if(z[i] == 0){
            unite(x[i], y[i]);
        }
    }
    ll cnt = 0;
    for(int i=0;i<n;i++){
        if(find(i) == i)cnt++;
    }
    //p(cnt);
    if(m < n && one){
        dame = true;
    }
    if(m > n - cnt + cnt * (cnt - 1) / 2){
        dame = true;
    }
    if(cnt <= 2 && one){
        dame = true;
    }
    for(int i=0;i<q;i++){
        if(z[i] == 1){
            if(m == n - 1)dame = true;
            if(same(x[i], y[i])){
                dame = true;
            }
        }
    }
    for(int i=0;i<n;i++){
        size[find(i)]++;
    }
    Yes(!dame);
    return 0;
}

















Measured memory_bytes: 33920