Find the maximum sum of a subsequence with the constraint

Question

Hi..........

Ques: Now i have write the program in c# but i am not get a output please solve the problem ....
 Given an array all of whose elements are positive numbers, find the maximum sum of a subsequence with the  constraint that no 2 numbers in the sequence should be adjacent in the array. So 3 2 7 10 should return 13 (sum of 3  and 10) or 3 2 5 10 7 should return 15 (sum of 3, 5 and 7)