#include<cstdio>
const int N=20010,M=100010,E=1200000;
int Case,cas,n,m,i,x,y,g[N],v[N<<1],nxt[N<<1],ed,ans;
int d[N],G[N],V[M<<1],NXT[M<<1],ED;
int f[N],size[N],son[N],top[N],loc[N],dfn,q[N];
int T[N],l[E],r[E],tag[E],val[E],pool[E],cur,w[66000];
inline void add(int x,int y){v[++ed]=y;nxt[ed]=g[x];g[x]=ed;}
inline void ADD(int x,int y){d[x]++;V[++ED]=y;NXT[ED]=G[x];G[x]=ED;}
inline void umin(int&a,int b){a>b?(a=b):0;}
inline int min(int a,int b){return a<b?a:b;}
void dfs(int x){size[x]=1;for(int i=g[x];i;i=nxt[i])if(v[i]!=f[x]){f[v[i]]=x;dfs(v[i]);size[x]+=size[v[i]],d[x]+=d[v[i]];if(size[v[i]]>size[son[x]])son[x]=v[i];}if(x>1)for(int i=g[x];i;i=nxt[i])if(v[i]!=f[x])umin(ans,d[x]-d[v[i]]);
}
void dfs2(int x,int y){loc[x]=++dfn;top[x]=y;if(son[x])dfs2(son[x],y);for(int i=g[x];i;i=nxt[i])if(v[i]!=son[x]&&v[i]!=f[x])dfs2(v[i],v[i]);
}
void build(int x,int a,int b){if(a==b){w[x]=q[a];return;}int mid=(a+b)>>1;build(x<<1,a,mid),build(x<<1|1,mid+1,b);w[x]=min(w[x<<1],w[x<<1|1]);
}
inline int newnode(int o){int x=pool[cur--];l[x]=r[x]=tag[x]=0;val[x]=w[o];return x;
}
inline void tag1(int x,int p){tag[x]+=p;val[x]+=p;}
inline void pb(int x,int o){if(tag[x]){if(!l[x])l[x]=newnode(o<<1);if(!r[x])r[x]=newnode(o<<1|1);tag1(l[x],tag[x]),tag1(r[x],tag[x]),tag[x]=0;}
}
inline void up(int x,int o){if(!l[x])l[x]=newnode(o<<1);if(!r[x])r[x]=newnode(o<<1|1);val[x]=min(val[l[x]],val[r[x]]);
}
void change(int&x,int o,int a,int b,int c,int d,int p){if(!x)x=newnode(o);if(c<=a&&b<=d){tag1(x,p);return;}pb(x,o);int mid=(a+b)>>1;if(c<=mid)change(l[x],o<<1,a,mid,c,d,p);if(d>mid)change(r[x],o<<1|1,mid+1,b,c,d,p);up(x,o);
}
inline void chain(int&T,int x){while(top[x]!=1)change(T,1,1,n,loc[top[x]],loc[x],-2),x=f[top[x]];if(x>1)change(T,1,1,n,2,loc[x],-2);
}
int merge(int x,int y,int o,int a,int b){if(!x||!y)return x+y;if(a==b)tag[x]+=tag[y];else{pb(x,o),pb(y,o);int mid=(a+b)>>1;l[x]=merge(l[x],l[y],o<<1,a,mid);r[x]=merge(r[x],r[y],o<<1|1,mid+1,b);up(x,o);}pool[++cur]=y;return x;
}
void clear(int x,int a,int b){if(!x)return;pool[++cur]=x;if(a==b)return;int mid=(a+b)>>1;clear(l[x],a,mid),clear(r[x],mid+1,b);
}
void dfs3(int x){if(son[x])dfs3(son[x]),T[x]=T[son[x]];for(int i=g[x];i;i=nxt[i])if(v[i]!=son[x]&&v[i]!=f[x])dfs3(v[i]),T[x]=merge(T[x],T[v[i]],1,1,n);if(x==1)return;for(int i=G[x];i;i=NXT[i])chain(T[x],V[i]);change(T[x],1,1,n,loc[x],loc[x],M);umin(ans,d[x]+val[T[x]]);change(T[x],1,1,n,loc[x],loc[x],-M);
}
int main(){for(i=1;i<E;i++)pool[++cur]=i;scanf("%d",&Case);for(cas=1;cas<=Case;cas++){scanf("%d%d",&n,&m);ans=M;for(i=1;i<n;i++)scanf("%d%d",&x,&y),add(x,y),add(y,x);for(;i<=m;i++)scanf("%d%d",&x,&y),ADD(x,y),ADD(y,x);dfs(1),dfs2(1,1);for(i=1;i<=n;i++)q[loc[i]]=d[i];build(1,1,n);dfs3(1);printf("Case #%d: %d\n",cas,ans+2);clear(T[1],1,n);for(ed=ED=dfn=0,i=1;i<=n;i++)g[i]=d[i]=G[i]=f[i]=size[i]=son[i]=T[i]=0;}return 0;
}