//GNC
#include <iostream>
#include <string>
#include <map>
#include <algorithm>
#include <vector>
#include <fstream>
#include <set>

using namespace std;

typedef vector<int> array;

int main(void){
  int N;
  ifstream cin("jurassic.in");
  while(cin >> N && N != 0){
    vector<string> bones;
    for(int i = 0 ; i < N ; i ++){
      string s;
      cin >> s;
      bones.push_back(s);
    }
    vector<int> bones_bit(N);
    for ( int i=0 ; i<N ; i++ ) {
      int b=0;
      string &s=bones[i];
      for ( int j=0 ; j<s.size() ; j++ )
	b |= 1<<(s[j]-'A');
      bones_bit[i]=b;
    }
    
    int maxbones = 0;
    //vector<int> maxboness;
    int max_i=0;
    for(int i = 0 ; i < (1 << bones.size()) ; i ++){
      int j = i;
      //map<char,int> counter;
      int counter=0;
      int taken=0;
      for(int t = 0 ; t < bones.size() ; t ++){
	if(j % 2 == 0){
	  /*for(int k = 0 ; k < bones[t].size() ; k++){
	    counter[bones[t][k]] ++;
	    }*/
	  counter ^= bones_bit[t];
	  taken++;
	}
	j /= 2;
      }
      /*bool succeed = true;
      for(int t = 'A' ; t <= 'Z' ; t++){
	if(counter[t]%2 == 1){
	  succeed = false;
	}
	}*/
      if(counter==0 ) {//succeed == true){
	if(taken > maxbones){
	  maxbones = taken;
	  max_i = i;
	}
      }
    }
    cout << maxbones << endl;
    if(maxbones > 0){
      int j=max_i;
      vector<int> maxboness;
      for ( int t=0 ; t<bones.size() ; t++ ) {
	if ( j%2==0 )
	  maxboness.push_back(t);
	j /= 2;
      }
      for(int i = 0 ; i < maxbones ; i ++){
	if(i == 0){
	  cout << maxboness[i] + 1;
	}
	else{
	  
	  cout << " " << maxboness[i] + 1;
	}
      }
    }
    cout << endl;
  }
}