how to make user to fill in at most value of 1 inside
cell c3,c4,c5.
This means if c3 is inserted 1, c4 n c5 will auto set to 0.
Or if c4 is inserted 1, c3 n c5 will set to 0.
Or if c5 is inserted 1, c3 n c4 will set to 0.

thank