component c1 {
  system {
    c2 ci2;
    c3 ci3;
  }
}

component c2 {
  system {
    c5 ci5;
  }
}

component c3 {
  system {
    c4 ci4;
    c2 ci2;
  }
}

component c4 {
  system {
    c1 ci1;
  }
}

component c5 {
  system { } // an empty system
}
