Let \( W_1 \) and \( W_2 \) be subspaces of the real vector space \( \mathbb{R}^{100} \) defined by
\[
W_1 = \{ (x_1, x_2, \dots, x_{100}) : x_i = 0 \text{ if } i \text{ is divisible by } 4 \},
\]
\[
W_2 = \{ (x_1, x_2, \dots, x_{100}) : x_i = 0 \text{ if } i \text{ is divisible by } 5 \}.
\]
Then the dimension of \( W_1 \cap W_2 \) is