Find the spectrum of the operator $$ \begin{split} A & \colon C[0,1] \rightarrow C[0,1] \\ & f \mapsto (Af)(x) := f(x) + \int_0^x f(t)dt \end{split} $$
P.S.: I know the spectrum of $A_1\colon f \mapsto \int_0^x f(t)dt$
Find the spectrum of the operator $$ \begin{split} A & \colon C[0,1] \rightarrow C[0,1] \\ & f \mapsto (Af)(x) := f(x) + \int_0^x f(t)dt \end{split} $$
P.S.: I know the spectrum of $A_1\colon f \mapsto \int_0^x f(t)dt$