[sdaf,sdg,dgs,t34,g43,fg24,vds234]

1.  a                   3. helyes zárójelezések
    ava                     ()
    avava                   ()()
    avavava......           (())
                            (((()))(())())

        a(va)*

        S -> aA
        A -> eps | vaA

        S -> a | avS

        S -> a | Sva

        S -> a | SvS

int i; i = 3; ...;

2.  ap
    apap
    apapap
    apapapap
    apapapapap......

        (ap)+

        S -> apA
        A -> eps | apA

        S -> ap | apS

        S -> ap | Sap

        S -> ap | SS

3.
    ()
    ()()()()()()()()()
    (((((())))))
    (((()))(())())

    S -> (S)S | eps