Let f(x₃,x₂,x₁,x₀) = (y₁,y₀) such that y₁ = 1 if the number of 1s in x₃x₂x₁x₀ is even, 0 otherwise, and, output y₀ = 1 if the number of 1s in x₃x₂x₁x₀ is odd, 0 otherwise. 1. (20 points) Implement f with four 2-to-4 decoders.

2. (20 points) Implement f with a 4-to-1 multiplexer with selection inputs x₀,x₁ (in this order).