The problem is simple, and the error message already hinted as to what it is. Line 9 is as follows:
else cout<<a&(-a)<<endl;
Now you probably think that this line is supposed to be parsed as (note extra parentheses) this:
else cout<< (a&(-a)) <<endl;
However, it's being parsed as this:
else (cout<<a) & ((-a)<<endl);
The compiler doesn't know what to do with the expression (-a)<<endl. The left-hand side of the expression, (-a), is an int, while the right-hand side, endl, is what the compiler sees as an <unresolved overloaded function type>, hence the error message.
There are several other problems with your code.
- Never use - #include <bits/stdc++.h>. It is non-standard and only works with some compilers: Why should I not #include <bits/stdc++.h>?
 
- The declaration for function - main()is wrong. Its return type must be an- int. Anything else is non-standard: What is the proper declaration of main in C++?
 
- The expression - a==a&(-a)may not do what you want. You may think that it means- a == (a&(-a))(again, note extra parentheses), when instead it means- (a==a) & (-a).