#include <iostream>
using namespace std;

int main() {
	// your code goes here
	long long n1, n2, n3, arr[1000000], k, count=0, n;
	cin>>n1>>n2>>n3; n=n1+n2+n3;
	for(int i=0; i<1000000; i++) arr[i]=0;
	while(n--) {cin>>k; arr[k]++;}
	for(int i=0; i<1000000; i++) if(arr[i]>1) count++;
	cout<<count<<endl;
	for(int i=0; i<1000000; i++) if(arr[i]>1) cout<<i<<endl;
	return 0;
}