void abort() { };
                                                                                                                                                          
                                                                            
extern unsigned short __VERIFIER_nondet_ushort();

/*@ 
    requires ((cond != 0)) && (cond != 0);
    ensures ((cond != 0)) && (1);
@*/
void __VERIFIER_assert(int cond) {
  if (!(cond)) {
    ERROR: {/*@ assert(0); */;abort();}
  }
  return;
}

int main() {
  unsigned int x = 0;
  unsigned short N = __VERIFIER_nondet_ushort();

/*@
loop invariant (((x % 2) == 0));
@*/
  while (x < N) {
    x += 2;
  }

  __VERIFIER_assert(!(x % 2));
}