PROCEDURE BINSRCH(N:INTEGER;L:LL;X:INTEGER;VAR Y:INTEGER);
    VAR K,M,J:INTEGER;
    BEGIN
      Y:=0;
      K:=1;
      M:=N;
      WHILE K <= M DO
        BEGIN
          J:=(K+M) DIV 2;
          IF X = L[J] THEN Y:=J;
          IF X < L[J] THEN M:=J-1
                        ELSE K:=J+1
        END
      END;