(* 2.2 *)
let power30 x = 
   let square x = x*x in
   let power5 x = 
      square(square x) * x in
         power5 (power5 x) * power5 x;;

(*2.3*)
let mirror x = 
   let u = x mod 10 and d= x/10 in
      u*10+d;;

let abba x = x*100+mirror;;

let stammer x = abba(mirror x)*10000 + abba x;;

(*2.6*)
let sec_of_time h m s = h*3600+m*60+s;;
let time_to_sec s = (s/3600, s mod 3600/60, s mod 3600 mod 60);;
let add_time ha ma sa hb mb sb = time_of_sec(sec_of_time ha ma sa + sec_of_time hb mb sb);;

(*3.3*)
let min2 a b =
   if a > b then b
   else a;;

let max2 a b = 
   if a > b then a
   else b ;;

let max3 a b c = if a>b && a>c then a else if b>c then b else c;;
let min3 a b c = if a<b && a<c then a else if b<c then b else c;;


(*3.7*)
let s a = match a with 
	x when x <= 0 -> 0.
	| x when x <= 500 -> 4.6
	| x when x <= 1000 -> 5.9
	| x when x <= 2000 -> 6.5
	| x when x <= 3000 -> 7.2
	| _ -> failwith "";;
let e a = match a with
        x when x <= 0 -> 0.
        | x when x <= 500 -> 3.4
        | x when x <= 1000 -> 4.6
        | x when x <= 2000 -> 5.1
        | x when x <= 3000 -> 6.9
        | _ -> failwith "";;
let ex a = match a with
        x when x <= 0 -> 0.
        | x when x <= 500 -> 9.1
        | x when x <= 1000 -> 11.
        | x when x <= 2000 -> 13.5
        | x when x <= 3000 -> 14.2
        | _ -> failwith "";;