void Fact(void){
  int local_var;
  local_var=global_var;
  if (global_var==1) return;
  if(global_var==0){ // Check if the input is 0.
    global_var=1;
    return;
  }
  if(global_var<0){ // Check if the input is less than zero.
    global_var=-1; // Assign global_var to a value that would not occur as the result of a factorial computation.
    return;
  }
  else {
    global_var=global_var-1;
    Fact();
    global_var=global_var*local_var;
    return;
  }
}