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