#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#define ll long long
using namespace std;
template <class T>
inline void rd(T &x)
{
	x=0; char c=getchar(); int f=1;
	while(!isdigit(c)){if(c=='-')f=-1; c=getchar();}
	while(isdigit(c)) x=x*10-'0'+c,c=getchar(); x*=f;
}
const int N=1e5+10;
int fa[N],n,q;
ll m;
struct Que { int x,y,c; }Q[N];
int find(int x) { return fa[x]==x?x:fa[x]=find(fa[x]); }
void FAIL() {
	printf("No");
	exit(0);
}
int main() {
	rd(n),rd(m),rd(q);
	for(int i=1;i<=n;++i) fa[i]=i;
	for(int i=1;i<=q;++i) {
		rd(Q[i].x),rd(Q[i].y),rd(Q[i].c);
		Q[i].x++,Q[i].y++;
		if(Q[i].c==0)
			fa[find(Q[i].x)]=find(Q[i].y);
	}
	int flg=0;
	for(int i=1;i<=q;++i) if(Q[i].c==1) {
		flg=1;
		if(find(Q[i].x)==find(Q[i].y)) FAIL();
	}
	int M=0;
	for(int i=1;i<=n;++i) M+=find(i)==i;
	if(m>M*(ll)(M-1)/2+(n-M)) FAIL();
	if(flg&&m<n) FAIL();
	printf("Yes");
	return 0;
}