Program dijkstra;
type lista = ^celula;
     celula = record
                    nod : longint;
                    cost : longint;
                    pred : lista;
               end;
const INF=200000000;
var Lda : array [1..50005] of lista;
    r  :lista;
    H,D: array [1..50005] of longint;
    n,i,a,b,c,v,k,aux1,p,lungime,aux: longint;
    b1,b2 : array[0..1 shl 17] of char;

procedure coboara(k : longint);
  var fiu,aux : longint;
    begin
         repeat
               fiu:=0;
               if k*2<=lungime then
                  begin
                       fiu:=k*2;
                       if  (k*2<lungime) then
                           if (D[H[k*2+1]]<D[H[k*2]]) then fiu:=k*2+1;
                       if D[H[fiu]]>=D[H[k]] then fiu:=0
                  end;
                  if fiu<>0 then begin
                                       aux:=H[k];
                                       H[k]:=H[fiu];
                                       H[fiu]:=aux;
                                       k:=fiu;
                                 end;

         until fiu=0;
   end;

begin
   assign(input,'darb.in'); settextbuf(input,b1); reset(input);
   assign(output,'darb.out'); settextbuf(output,b2); rewrite(output);
   readln(n); aux1:=n;
   while not seekeof do begin
                        readln(a,b);
                        new(r);
                        r^.nod:=b;
                        r^.cost:=1;
                        r^.pred:=lda[a];
                        lda[a]:=r;
                        new(r);
                        r^.nod:=a;
                        r^.cost:=1;
                        r^.pred:=lda[b];
                        lda[b]:=r;
                    end;
   for i:=2 to n do D[i]:=INF;

   H[1]:=1;
   lungime:=1;
   while lungime>0 do begin
                          v:=H[1];
                          r:=lda[v];
                          H[1]:=H[lungime];
                          lungime:=lungime-1;
                          coboara(1);
   while r<>nil do begin
                    if D[v]+r^.cost<D[r^.nod] then begin
                                                      D[r^.nod]:=D[v]+r^.cost;
                                                      lungime:=lungime+1;
                                                      H[lungime]:=r^.nod;
                                                      k:=lungime;
       while (k>1) and (D[H[k]]<D[H[k div 2]]) do begin
                                                      aux:=H[k];
                                                      H[k]:=H[k div 2];
                                                      H[k div 2]:=aux;
                                                      k:=k div 2;
                                                  end;
                                                    end;
                        r:=r^.pred;
                    end;

                   end;
       writeln(D[n]+D[n-1]+1);
   close(input);
   close(output);
end.