#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

int main()
{
  ifstream cin("jurassic.in");
  for (int n;cin>>n,n!=0;){
    int v[24];
    for (int i=0;i<n;i++){
      string t;cin>>t;
      int u=0;
      for (int j=0;j<t.length();j++)
        u|=(1<<(t[j]-'A'));
      v[i]=u;
    }
    int mcnt=0,mpat=0;
    int tbl[26]={0};
    for (int i=1;i<(1<<n);i++){
      int cnt=0;
      for (int j=0;j<n;j++) if (i&(1<<j)) cnt++;
      if (cnt<=mcnt) continue;

      int tmp=0;
      for (int j=0;j<n;j++)
        if (i&(1<<j))
          tmp^=v[j];

      if (tmp==0){
        if (mcnt<cnt){
          mcnt=cnt;
          mpat=i;
        }
      }
    }
    cout<<mcnt<<endl;
    bool fst=true;
    for (int i=0;i<n;i++){
      if (mpat&(1<<i)){
        if (fst) fst=false;
        else cout<<" ";
        cout<<i+1;
      }
    }
    cout<<endl;
  }
  return 0;
}