Premise: A is containing all values in range [1, 4] except one: Let's say that, without loss of generality: > 1 ^ 2 ^ 3 ^ 4 ^ A[0]=1 ^ A[1]=2 ^ A[2]=3 ^ A[3]=

Premise: A is containing all values in range [1, 4] except one: Let's say that, without loss of generality: > 1 ^ 2 ^ 3 ^ 4 ^ A[0]=1 ^ A[1]=2 ^ A[2]=3 ^ A[3]=4 However, A is now missing no value. Contradiction. ∎