All columns values in one column

I need some help! :SI have a spreadsheet and three list of items (Column "A", "B" and "C") and I need to put all the values of all the columns in only one column (Column "E"). A picture is following here... I tried everything I could but the true is that I'm not an expert in sheets. So if you can help me to simplify this with a fonction or formula or a miracle :S lol... it would be really appreciated. I really Hope you can help me.