d1,d2,d3=map(int,input().split())
l1=[]
l2=[]
l3=[]
for i in range(d1):
l1.append(int(input()))
for i in range(d2):
l2.append(int(input()))
for i in range(d3):
l3.append(int(input()))
b1=list(set(l1)&set(l2))
b2=list(set(l2)&set(l3))
b3= list(set(l1)&set(l3))
res=set(b1+b2+b3)
print(len(res))
res=list(res)
for i in range(len((res))):
print(res[i])