anyone can think of any solution how to find a lowest cost of project management (CPM)

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C#

i got lists of data

list proj_name = { A,B,C,D,E,F}
list duration = { 6,10,5,4,9,2}
list fastest_duration = {6,8,4,1,7,1}
list cost = {-,500,300,700,600,800}

if critical path was A-B-F and C-D-E-F

i know that we can use intersec to find the same proj_name but it can't be use if there was more than 2 Critical path any know how to find it ?

the cost per day was 1150