I have two lists such as 

List1 = {0.1,1,2,3,4,5,6,7,8,9,10,11,12}

List2 = {0.1,2,4,6,7,10}

What I would like to do is create a intersection of above two lists

Final_list =( List1 - List2)  = { 1 ,2 ,3 ,4 ,5 ,6 } - { 2, 4, 6}  = {  1 ,3 ,5  }

then input the first index of Final_list in the  Channel_No  field , that means 

input. Channel_No = 1;

Please help me how to write the script to achieve it

Thanks

Arfater