VAR x,y,z, q,r, n,f;

PROCEDURE multiply;
   VAR a,b;
BEGIN a := x; b := y; z := 0;
   WHILE b > 0 DO
   BEGIN IF ODD z THEN z := z + a;
        a := 2*a; b := b/2
   END
END ;

PROCEDURE divide;
   VAR w;
BEGIN r := x; q := 0; w := y;
   WHILE w <= r do  w := 2*w;
   WHILE w > y do
   BEGIN q := 2*q; w := w/2;
      IF w <= r THEN
         BEGIN r := r - w ; q := q + 1
         END
   END
END ;

PROCEDURE gcd;
   VAR f,g;
BEGIN f := x; g := y;
   WHILE f # g DO
      BEGIN IF f < g THEN g := g - f;
            IF g < f THEN f := f - g;
      END ;
   z := f
END ;

PROCEDURE fact;
BEGIN
  IF n > 1 THEN
    BEGIN f := n*f; n := n-1; CALL fact
    END
END ;

BEGIN
   ?x; ?y; CALL multiply; !z;
   ?x; ?y; CALL divide; !q; !r;
   ?x; ?y; CALL gcd; !z;
   ?n; f := 1; CALL fact; !f
END .