I used classic formula but for some reasone I always get WA. Thanks!

Var
   N,M,Ost,NSD,Bil,Men : Longint;
Begin
Read(N);Read(M);
Bil:=N;Men:=M;
While Bil Mod Men <>0 Do Begin
Ost:=Bil Mod Men;
Bil:=Men;
Men:=Ost;
End;
NSD:=Men;
Writeln(N+M-NSD);
End.