#include<bits/stdc++.h>
#define MN 100000
#define ll long long
using namespace std;
inline int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
ll m;
pair<int,int> a[MN+5];
int n,Q,s[MN+5],num,ans;
inline int getfa(int x){return s[x]?s[x]=getfa(s[x]):x;}
inline void Merge(int x,int y){if(getfa(x)!=getfa(y)) s[getfa(x)]=getfa(y);}
int main()
{
    n=read();cin>>m;Q=read();
    for(int i=1;i<=Q;++i)
    {
        int x=read()+1,y=read()+1,op=read();
        if(op==0) Merge(x,y);
        else a[++num]=make_pair(x,y);
    }
    for(int i=1;i<=num;++i) 
        if(getfa(a[i].first)==getfa(a[i].second)) return 0*puts("No");
    if(m==n-1) return 0*puts(num?"No":"Yes");
    for(int i=1;i<=n;++i) if(getfa(i)==i) ++ans;
    if(ans==2)
    {
        if(num) return 0*puts("No");
        else if(m>n-1) return 0*puts("No");
        else return 0*puts("Yes");
    }
    long long max=1LL*ans*(ans-1)/2;
    if(n-ans+max<m) return 0*puts("No");
    puts("Yes");
    return 0;
}