Program DF;
type lista = array[0..1, 1..50] of integer;
     pornire = array[1..50] of integer;
var n: integer;
    s: array[1..50] of integer;
    t: lista;
    start: pornire;

procedure Citire_LA_Astatic(nume_fis: string; var t: lista; var start: pornire; var n: integer);
var i, j, k: integer;
    f: text;
begin
    k := 0;
    Assign(f, nume_fis);
    Reset(f);
    Readln(f, n);
    while(not eof(f)) do
    begin
        Readln(f, i, j);
        k := k + 1;
        t[0,k] := j;
        t[1,k] := start[i];
        start[i] := k;
        k := k + 1;
        t[0,k] := i;
        t[1,k] := start[j];
        start[j] := k;
    end;
    Close(f);
end;

procedure DF(nod: integer);
var p: integer;
begin
    WriteLn(nod, ' ');
    p := start[nod];
    s[nod] := 1;
    while p <> 0 do
    begin
        if s[t[0,p]] = 0 then
            DF(t[0,p]);
        p := t[1,p];
    end
end;

begin
    Citire_LA_Astatic('Graf.txt', t, start, n);
    DF(1);
end.