text: 
  void recv()
  void send()
  void init()
  int nondet()
  
  void C1() {
    int a = nondet();
    if (a > 0) {
      send();
      recv();
    }
  }
  
  void C2() {
    int a = nondet();
    if (a > 0) {
      send();
    }
    recv();
  }
  
  void main() {
    C1(); C2();
  }
  