5. There is a program written in C syntax: int a 5 int flO fa 14; return 9;3 int f20 fa 11; return 2;) void f3() {a = f1 () + a + f2();} main) f30: a) (10) The function f30 has a side effect. Explain why the function has a side effect. b) (15) Rewrite a function f30 definition to avoid the side effect