Cell-counting factor that limits the maximum size of the multicellular structure. May down-regulate the expression of gp24, which mediates cell adhesion. Component of the counting factor (CF) complex, which includes cf60, cf50, cf45-1 and ctnA. Highly expressed in the vegetative cells and decreases during subsequent developmental stages (6-24 hours). Cells form a fewer number of larger aggregates. Belongs to the countin family.