#include<stdio.h>
#include<iostream>
#include<map>
#include<string>
#include<list>
#include<stack>

using namespace std;

int main()
{
    int x,t;
    scanf("%d",&t);

    for (x=1; x<=t; ++x)
    {
        map <string,int> id;
        map <int,string> word;
        list <int> synlist[2001];
        list <int> antlist[2001];

        int n, i, j, m, num= 0,synarr[2001],antarr[2001],k= 0,l= 0;
        bool synstore[2001][2001]= {0}, antstore[2001][2001]= {0};
        char s[1000],s1[30],s2[30];

        scanf("%d%d",&n,&m);
        getchar();

        while (n--)
        {
              scanf("%[^\n]",s);
              //puts(s);
              sscanf(s,"%s %s",s1,s2);
              //puts(s1);
              //puts(s2);
              if (!id[s1]) id[s1]= ++num;
              synarr[++k]= num;
              if (!id[s2]) id[s2]= ++num;
              synarr[++k]= num;
              synlist[ id[s1] ].push_back(id[s2]);
              synlist[ id[s2] ].push_back(id[s1]);
              synstore[ id[s1] ][ id[s2] ]= 1;
              synstore[ id[s2] ][ id[s1] ]= 1;

              word[ id[s1] ]= s1;
              word[ id[s2] ]= s2;
              getchar();
        }
        while (m--)
        {
              scanf("%[^\n]",s);
              sscanf(s,"%s %s",s1,s2);
              //puts(s);
              //puts(s1);
              //puts(s2);
              if (!id[s1]) id[s1]= ++num;
              antarr[++l]= num;
              if (!id[s2]) id[s2]= ++num;
              antarr[++l]= num;
              antlist[ id[s1] ].push_back(id[s2]);
              antlist[ id[s2] ].push_back(id[s1]);
              antstore[ id[s1] ][ id[s2] ]= 1;
              antstore[ id[s2] ][ id[s1] ]= 1;

              word[ id[s1] ]= s1;
              word[ id[s2] ]= s2;
              getchar();
        }
        int start,end;
        bool flag= 0;

        for (i=1; i<=l; ++i)
        {
            start= antarr[i];

            list <int> ::iterator it;
            list <int> ::iterator it2;

            for (it= antlist[start].begin(); it!= antlist[start].end(); ++it)
            {
                for (it2= antlist[*it].begin(); it2!= antlist[*it].end(); ++it2)
                {
                    synlist[start].push_back(*it2);
                    synlist[*it2].push_back(start);
                    synstore[start][*it2]= 1;
                    synstore[*it2][start]= 1;

                    if (antstore[start][*it2])
                    {
                       flag= 1;
                       break;
                    }
                }
                if (flag) break;
            }
            if (flag) break;
        }

        if (!flag)
        {
           bool index[4001]= {0};
           int nodes= 0, set[4001], p= 0;

           for (i=1; i<=k; ++i)
           {
               start= synarr[i];

               if (index[start]) continue;
               p= 0;
               index[start]= 1;
               set[++p]= start;
               nodes++;

               stack <int> act;
               stack <int> wait;
               wait.push(start);

               do
               {
                 while (!wait.empty())
                 {
                       act.push( wait.top() );
                       wait.pop();
                 }
                 while ( !act.empty() )
                 {
                       start= act.top();
                       act.pop();

                       list <int> ::iterator it;
                       for (it= synlist[start].begin(); it!= synlist[start].end(); ++it)
                       {
                           if (index[*it]) continue;
                           index[*it]= 1;
                           set[++p]= *it;
                           wait.push(*it);
                           nodes++;
                           if (nodes==k) break;
                       }
                       if (nodes==k) break;
                 }
                 if (nodes==k) break;
               }
               while (!wait.empty());

               //for (j=1; j<=p; ++j) cout << word[ set[j] ] << "<<" ;
               //puts("");

               for (j=1; j<=p; ++j)
               {
                   for (l=1; l<=p; ++l)
                   {
                       if (j==l) continue;

                       synstore[ set[j] ][ set[l] ]= 1;
                       synstore[ set[l] ][ set[j] ]= 1;
                       //cout << word[set[j]] << " " << word[set[l]] << endl;

                       if (antstore[ set[j] ][ set[l] ])
                       {
                          //cout << word[set[j]] << " " << word[set[l]] << endl;
                          flag= 1;
                          break;
                       }
                   }
                   if (flag) break;
               }
               if (flag || nodes==k) break;
           }
        }



        // outputs
        printf("Case %d: ",x);
        if (flag) puts("NO");
        else puts("YES");
    }
    return 0;
}