need help in sum up multi criterias (index & match)

Hi all,

Please find the screenshot in attached file.

I have 4 customer in the list. Each customer can have more than 1 security number.

as per example in the file, for customer 2, security number are same. so i will look at the security type, if the security type is different, then i will sum up both security amount. if the security type is same, then i will take the highest security amount. if the security amount is same, i will oni take 1 amount.

how should i write the formula? i have 3000+ lines to go. can i use index & match function?

thanks