import sys
input = sys.stdin.readline

T=int(input())
for tests in range(T):
    W,E,C=map(int,input().split())

    X=list(map(int,input().split()))
    Y=list(map(int,input().split()))

    Q=[list(map(int,input().split())) for i in range(C)]

    ANS=[]

    for a,b in Q:
        EDGE=[[] for i in range(W+E)]

        for i in range(W-1):
            EDGE[i].append(X[i]-1)
            EDGE[X[i]-1].append(i)

        for i in range(E-1):
            EDGE[i+W].append(Y[i]-1+W)
            EDGE[Y[i]-1+W].append(i+W)

        EDGE[a-1].append(b-1+W)
        EDGE[b-1+W].append(a-1)

        #print(EDGE)

        ROOT=0
        N=W+E

        QUE=[ROOT] 
        Parent=[-1]*N
        Parent[ROOT]=N # ROOTの親を定めておく.
        Child=[[] for i in range(N)]
        TOP_SORT=[] # トポロジカルソート

        while QUE: # トポロジカルソートと同時に親を見つける
            x=QUE.pop()
            TOP_SORT.append(x)
            for to in EDGE[x]:
                if Parent[to]==-1:
                    Parent[to]=x
                    Child[x].append(to)
                    QUE.append(to)

        Children=[1]*N

        for x in TOP_SORT[::-1]: #（自分を含む）子ノードの数を調べる
            if x==ROOT:
                break
            Children[Parent[x]]+=Children[x]

        #print(Children)

        score=0

        for x in TOP_SORT[::-1]: #（自分を含む）子ノードの数を調べる
            if x==ROOT:
                break
            p=Parent[x]

            score+=Children[x]*(N-Children[x])

        #print(N,score)

        ANS.append(score/(N*(N-1)//2))

    ANS=" ".join(map(str,ANS))

    print("Case #"+str(tests+1)+": "+str(ANS))