equal(word(A,B,C,D,E), word(F,G,H,I,J)) :-
    word(A,B,C,D,E),
    word(F,G,H,I,J),
    A==F, B==G, C==H, D==I, E==J.

equalbutone(word(A,B,C,D,E), word(F,G,H,I,J)) :-
    word(A,B,C,D,E),
    word(F,G,H,I,J),
    \+A==F, B==G, C==H, D==I, E==J.

equalbutone(word(A,B,C,D,E), word(F,G,H,I,J)) :-
    word(A,B,C,D,E),
    word(F,G,H,I,J),
    A==F, \+B==G, C==H, D==I, E==J.

equalbutone(word(A,B,C,D,E), word(F,G,H,I,J)) :-
    word(A,B,C,D,E),
    word(F,G,H,I,J),
    A==F, B==G, \+C==H, D==I, E==J.

equalbutone(word(A,B,C,D,E), word(F,G,H,I,J)) :-
    word(A,B,C,D,E),
    word(F,G,H,I,J),
    A==F, B==G, C==H, \+D==I, E==J.

equalbutone(word(A,B,C,D,E), word(F,G,H,I,J)) :-
    word(A,B,C,D,E),
    word(F,G,H,I,J),
    A==F, B==G, C==H, D==I, \+E==J.

trace(word(A,B,C,D,E), word(F,G,H,I,J)) :-
    word(A,B,C,D,E),
    word(F,G,H,I,J),
    equal(word(A,B,C,D,E), word(F,G,H,I,J)).

trace(word(A,B,C,D,E), word(F,G,H,I,J)) :-
    word(A,B,C,D,E),
    word(F,G,H,I,J),
    equalbutone(word(A,B,C,D,E), X),
    trace(X, word(F,G,H,I,J)).