let containStr (s2 : string) (s1 : string) : bool =
let rec inString s1 s2 l1 l2 =(
if (l1 < l2) then false
else(if(l1 = l2) then (s1=s2)
else(if((String.sub s1 0 l2)=s2)
then true
else inString (String.sub s1 1 (l1-1)) s2 (l1-1) l2))) in
let l1 = String.length s1 in
let l2 = String.length s2 in
inString s1 s2 l1 l2