count=int(input())
qdcounts=[]
qj=[]
for i in range(count):
	qdcounts.append(list(map(int,input().split())))
	for j in qdcounts[i]:
		for k in range(1,j+1):
			qj.append(list(map(int,input().split())))
j=-1
for i in range(count):
	hua=[]
	diao=[]
	a=qdcounts[i][0]
	b=qdcounts[i][1]
	for k in range(a):
		j+=1
		for p in range(qj[j][0],qj[j][1]+1):
			hua.append(p)
		hua1=[]
		for p in hua:
			if not (p in hua1):
				hua1.append(p)
	for k in range(b):
		j+=1
		for p in range(qj[j][0],qj[j][1]+1):
			diao.append(p)
		diao1=[]
		for p in diao:
			if not (p in diao1):
				diao1.append(p)
	s=0
	for k in hua1:
		if k in diao1:
			s+=1
	print(s)