Determine the number of satisfying truth assignments (out of $2^5 = 32$ possible assignments) for the 5-variable propositional formula: $\phi = (x_1 \implies x_2) \land (x_2 \implies x_3) \land (x_3 \implies x_4) \land (x_4 \implies x_5) \land (x_3 \implies \neg x_5)$