var n : int; n := string2int(read()); var x : int; var fact : int; fact := 1; begin var a_0 : int; x := 1; a_0 := n; while x <= a_0 do fact := x * fact; x := x + 1; end end write("factorial of "); write(int2string(n)); write(" is "); write(int2string(fact)); write("\n");