PROGRAM Graph(INPUT, OUTPUT);

TYPE
   NodeTyp = ^NodeRec;
   NodeRec = RECORD
		Value: CHAR;
		Neigh: ArcType;
	     END ;
   ArcTyp = ^ArcRec;
   ArcRec = RECORD
		Chld:  NodeTyp;
		Next:  ArcTyp;
	     END ;
   GraphTyp = ARRAY ['A'..'Z'] of NodeTyp ;

  PROCEDURE AddArc(VAR G: GraphTyp; Frum, Too: CHAR);
  VAR
    X: ArcTyp;
    N: NodeTyp;
    Done: Boolean;
  BEGIN
    X := G[From]^.Neigh;
    Done := FALSE;
    WHILE NOT(DONE) DO
     BEGIN
      IF X = NIL THEN
        DONE := TRUE
      ELSE IF X^.Chld^.Value >= Too THEN
        DONE := TRUE
      ELSE
        X := X^.Next
     END ;
    IF X = NIL THEN
     BEGIN
      NEW(N);

  PROCEDURE MAIN;
  VAR
    G: GraphTyp;
    X: NodeTyp;
    C, D: CHAR;
  BEGIN
    FOR C := 'A' TO 'Z' DO
     BEGIN
      NEW(X);
      X^.Value := C;
      X^.Neigh := NIL;
      G[C] := X
     END ;
    WHILE NOT EOF(INPUT) DO
     BEGIN
      READ(INPUT, C);
      GET(INPUT);
      GET(INPUT);
      READ(INPUT, D);
      AddArc(G, C, D)
     END ;

  END { MAIN } ;


BEGIN
  MAIN;
END {Graph} .