:- use_module(library(clpfd)).

abeceda([a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z]).

rotiraj(K, L, L) :-
    K #=< 0.
rotiraj(K, [A|B], C) :-
    K #> 0,
    K1 #= K - 1,
    append(B, [A], D),
    rotiraj(K1, D, C).

preslikaj([X|_], [Y|_], X, Y).
preslikaj([_|L1], [_|L2], X, Y) :-
    preslikaj(L1, L2, X, Y).

cezar(K, In, Out) :-
    abeceda(A),
    rotiraj(K, A, B),
    maplist(preslikaj(A, B), In, Out).

% ?- K in 0..25, label([K]), cezar(K, In, [y,p,f,y,j,z,u,f,h,u,b,q,x,u,a]).