id = \x->x ;

a = \f -> f id id ;
a = \f -> f a a ;
a = \f -> f a a ;
a = \f -> f a a ;
a = \f -> f a a ;
a = \f -> f a a ;
a = \f -> f a a ;
a = \f -> f a a ;
a = \f -> f a a ;
a = \f -> f a a ;
a = \f -> f a a ;
a = let f = a in \x -> x ;

b = \f -> f id id ;
b = \f -> f b b ;
b = \f -> f b b ;
b = \f -> f b b ;
b = \f -> f b b ;
b = \f -> f b b ;
b = \f -> f b b ;
b = \f -> f b b ;
b = \f -> f b b ;
b = \f -> f b b ;
b = \f -> f b b ;
b = let f = b in \x -> x ;

c = \f -> f id id ;
c = \f -> f c c ;
c = \f -> f c c ;
c = \f -> f c c ;
c = \f -> f c c ;
c = \f -> f c c ;
c = \f -> f c c ;
c = \f -> f c c ;
c = \f -> f c c ;
c = \f -> f c c ;
c = \f -> f c c ;
c = let f = c in \x -> x ;

d = \f -> f id id ;
d = \f -> f d d ;
d = \f -> f d d ;
d = \f -> f d d ;
d = \f -> f d d ;
d = \f -> f d d ;
d = \f -> f d d ;
d = \f -> f d d ;
d = \f -> f d d ;
d = \f -> f d d ;
d = \f -> f d d ;
d = let f = d in \x -> x ;