+ Filename.basename !problem_file);
+ let prefix = string_of_int (Unix.getpid ()) in
+ let prerr_endline s = prerr_endline (prefix ^ ": " ^ s) in
+ let times = Unix.times () in
+ prerr_endline ("solved " ^ !problem_file ^ " in " ^ string_of_float
+ (times.Unix.tms_utime +. times.Unix.tms_stime) ^ " using " ^ ord);