pk1,pk2,pk3,content
a,b,a,a-b-a
a,b,b,a-b-b
a,b,c,a-b-c
a,b,d,a-b-d
a,b,e,a-b-e
a,b,f,a-b-f
a,b,g,a-b-g
a,b,h,a-b-h
a,b,i,a-b-i
a,b,j,a-b-j
a,b,k,a-b-k
a,b,l,a-b-l
a,b,m,a-b-m
a,b,n,a-b-n
a,b,o,a-b-o
a,b,p,a-b-p
a,b,q,a-b-q
a,b,r,a-b-r
a,b,s,a-b-s
a,b,t,a-b-t
a,b,u,a-b-u
a,b,v,a-b-v
a,b,w,a-b-w
a,b,x,a-b-x
a,b,y,a-b-y
a,b,z,a-b-z