:- set_prolog_flag(double_quotes, chars).
lengelize :-
   L = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz",
   len_(L, 0,N),
   lenloop(L, N).

lenloop(L, N) :-
   len_(L, 0, M),
   N == M,
   lenloop(L, N).

len_([], N,N).
len_([_|L], N0,N) :-
   N1 is N0+1,
   len_(L, N1,N).