create one list from to two colums : in need Help with oracle SQL.

i have a table with

     from	to
     F	    B
     B	    R
     R	    D
     E	    X
     X	    Q

and i need the list

    F
    B
    R
    D
    E
    X
    Q

so my problem is the jump from R-->D to E-->X 

has anybody an idea ?



