Transpose values from column to rows (one cell) with conditions

Hello to all
I need formula or something else (mybe not a macro don't like it very much)
colum A and B are data. C is calculation column. in cell in column C i want all data of B for all rows in column A for same number.
In column A where is blank cell, there is a same number like in upper row

Hope understand! Thanks for help !

Please see attach!