pk1,pk2,pk3,content
b,a,p,b-a-p
b,b,p,b-b-p
b,c,p,b-c-p
b,d,p,b-d-p
b,e,p,b-e-p
b,f,p,b-f-p
b,g,p,b-g-p
b,h,p,b-h-p
b,i,p,b-i-p
b,j,p,b-j-p
b,k,p,b-k-p
b,l,p,b-l-p