Eliminate the space between grid rows

I’m trying to combine one 600×600 picture and four 300×300 pictures together, the 600×600 on the left and four 300×300 pictures on the right. I cannot insert a single picture because I need to set up a link for each picture. I’d like to eliminate all the space among pictures. However, I don’t want the combined picture to take up all the width. That means some space on the very left and right. What should I do?
p.s. I’m using grid row now and all the paddings are set to 0