def solve(self, A, B, C):

```
dic={}
for i in set(A):
if(i in dic):
dic[i]+=1
else:
dic[i]=1
for j in set(B):
if(j in dic):
dic[j]+=1
else:
dic[j]=1
for k in set(C):
if(k in dic):
dic[k]+=1
else:
dic[k]=1
A=set(A)
B=set(B)
C=set(C)
ans=[]
for m in dic:
if(m in A and m in B and m in C):
ans.append(m)
elif(m in A and m in B and m not in C):
ans.append(m)
elif(m in A and m not in B and m in C):
ans.append(m)
elif(m not in A and m in B and m in C):
ans.append(m)
else:
continue
ans.sort()
return(ans)
```