<image>(2012 Autumn•Donghai County School-level monthly exam) Given the universal set \(U = \mathbb{R}\), set \(M = \{x \mid -2 \le x - 1 \le 2\}\) and set \(N = \{x \mid x = 2k - 1, k = 1, 2, \ldots \}\). The Venn diagram of the relationship is shown in the figure. Then, the number of elements in the set represented by the shaded area is _____.