3 Input XNOR gate made with XOR and not gates
What you should get is an XNOR gate (Y=A'B'C'+ABC'+A'BC+AB'C) "an even number of ones". As an XOR gate will give an output that is true if and only if an "odd number of ones" is deriving it. So, inverting the XOR gate will results in an XNOR gate that will give an output which is true if and only if an "even number of ones" is deriving it.