Object doesn't exist in different scenario

In a condition, where i am using If....elseIf. I need to check more than 2 items to be exist or not. so i am doing like:
Set A = '(element page address)
Set B = '(element page address)

Set C = '(element page address)

but when execution comes to these lines, it gives me "Object doesn't exist". Please understand my question first. If that element exist on application Example:
1) If  A exists but B and C not, in that condition execution will go through all the lines Set A, Set B, Set C . Because object A exist so it will not give me error but for gone through B and C only it give me error like"Object doesn't exist".
Yes it will not effecting my script execution but i am getting error in test log, So how should i handle it