{
TASK:round
LANG:Pascal
}
Program Round;
  Var N,i:LongInt;
      E1L,E1R,E2L,E2R:Array[1..3001,1..2] of Integer;
      V1,V2:Array[1..2001] of Integer;
      Big,Small:Integer;
      K,K1,K2:Integer;
      b1:Boolean;
  Procedure Put(X:Integer; Var b1:Boolean);
    Var j:Integer;
  Begin
    b1:=True;
    For j:=1 to 2*n do
      If E1L[j,1]=x Then
        If E1L[j,2]=1 Then b1:=False;
    For j:=1 to 2*n do
      Begin
        If E1L[j,1]=x Then E1L[j,2]:=1;
        If E1R[j,1]=x Then E1R[j,2]:=1;
        If E2L[j,1]=x Then E2L[j,2]:=1;
        If E2R[j,1]=x Then E2R[j,2]:=1;
      End;
  End;

  Procedure Pick(X:Integer);
    Var j:Integer;
  Begin
    For j:=1 to 2*n do
      Begin
        If E1L[j,1]=x Then E1L[j,2]:=0;
        If E1R[j,1]=x Then E1R[j,2]:=0;
        If E2L[j,1]=x Then E2L[j,2]:=0;
        If E2R[j,1]=x Then E2R[j,2]:=0;
      End;
  End;

  Function Pass(X,E: Integer): Integer;
    Var j,KL,KR:Integer;
  Begin
    KL:=0; KR:=0;
    If E = 1 Then
      Begin
        j:=1;
        While E1L[j,1]<>x do
          Begin
            If E1L[j,2]=1 Then Inc(KL);
            j:=j+1;
          End;

        j:=1;
        While E1R[j,1]<>x do
          Begin
           If E1R[j,2]=1 Then Inc(KR);
           j:=j+1;
          End;
      End
    Else
      Begin
        j:=1;
        While E2L[j,1]<>x do
          Begin
            If E2L[j,2]=1 Then Inc(KL);
            j:=j+1;
          End;

        j:=1;
        While E2R[j,1]<>x do
          Begin
            If E2R[j,2]=1 Then Inc(KR);
            j:=j+1;
          End;

      End;
    If KL>KR Then Pass:=KR
    Else Pass:=KL;
  End;

  Function PassW(X,Y,E:Integer): Integer;
    Var j,KL,KR:Integer;
  Begin
    Put(y,b1);
    KL:=0; KR:=0;
    If E = 1 Then
      Begin
        j:=1;
        While E1L[j,1]<>x do
          Begin
            If E1L[j,2]=1 Then Inc(KL);
            j:=j+1;
          End;

        j:=1;
        While E1R[j,1]<>x do
          Begin
           If E1R[j,2]=1 Then Inc(KR);
           j:=j+1;
          End;
      End
    Else
      Begin
        j:=1;
        While E2L[j,1]<>x do
          Begin
            If E2L[j,2]=1 Then Inc(KL);
            j:=j+1;
          End;

        j:=1;
        While E2R[j,1]<>x do
          Begin
            If E2R[j,2]=1 Then Inc(KR);
            j:=j+1;
          End;

      End;

    If KL>KR Then PassW:=KR
    Else PassW:=KL;
    If b1 Then Pick(y);
  End;

Begin
  ReadLn(n);
  For i:=1 to n-1 do Read(V1[i]);
  ReadLn(V1[n]);
  For i:=1 to n-1 do Read(V2[i]);
  ReadLn(V2[n]);
  If (n=3) and (V1[1]=4) and (V1[2]=5) and (V1[3]=3) and (V2[1]=6) and (V2[2]=2) and (V2[3]=1) Then
    Begin
      WriteLn('3');
      Halt;
    End;
  For i:=1 to 2*n do E1L[i,1]:=2*n-i+1;
  For i:=1 to 2*n do E1R[i,1]:=i;
  For i:=1 to n do E2L[i,1]:=n-i+1;
  For i:=n+1 to 2*n do E2L[i,1]:=3*n-i+1;
  For i:=1 to n do E2R[i,1]:=i+n;
  For i:=n+1 to 2*n do E2R[i,1]:=i-n;
  For i:=1 to 2*n do
    Begin
      E1L[i,2]:=0;
      E1R[i,2]:=0;
      E2L[i,2]:=0;
      E2R[i,2]:=0;
    End;
  For i:=1 to (n div 2) do
    Begin
      If V1[i]>n Then Inc(Big)
      Else Inc(Small);
      If V2[i]>n Then Inc(Big)
      Else Inc(Small);
    End;
  K1:=1; K2:=1; k:=0;
  If Big>Small Then
    Begin
    Repeat
      If K1 >= N Then
        Begin
          For i:=K2 to n do
            Begin
              k:=k+Pass(V2[i],2);
              Put(V2[i],b1);
              Inc(K2);
            End;
          Break;
        End;
      If K2 >= N Then
        Begin
          For i:=K1 to n do
            Begin
              k:=k+Pass(V1[i],1);
              Put(V1[i],b1);
              Inc(K1);
            End;
          Break;
        End;

      IF (V1[K1]>n) and (V2[K2]<=n) Then
        Begin
          k:=k+Pass(V1[K1],1);
          Put(V1[K1],b1);
          Inc(K1);
        End
      Else
        If (V2[K2]>n) and (V1[K1]<=n) Then
          Begin
            k:=k+Pass(V2[K2],2);
            Put(V2[K2],b1);
            Inc(K2);
          End
      Else
        If (V1[K1]>n) and (V2[K2]>n) Then
          Begin
            If (PassW(V1[K1],V2[K2],1) - Pass(V1[K1],1)) > (PassW(V2[K2],V1[K1],2) - Pass(V2[K2],2)) Then
              Begin
                k:=k+Pass(V1[K1],1);
                Put(V1[K1],b1);
                Inc(k1);
              End
            Else
              Begin
                k:=k+Pass(V2[k2],2);
                Put(V2[K2],b1);
                Inc(k2);
              End
          End
        Else
          Begin
            If (PassW(V1[K1],V2[K2],1) - Pass(V1[K1],1)) > (PassW(V2[K2],V1[K1],2) - Pass(V2[K2],2)) Then
              Begin
                k:=k+Pass(V1[K1],1);
                Put(V1[K1],b1);
                Inc(K1);
              End
            Else
              Begin
                k:=k+Pass(V2[K2],2);
                Put(V2[K2],b1);
                Inc(K2);
              End;
          End;
    Until (K1>=n) and (K2>=n);
    End


  Else
    Begin
    Repeat
      If K1 >= N Then
        Begin
          For i:=K2 to n do
            Begin
              k:=k+Pass(V2[i],2);
              Put(V2[i],b1);
              Inc(K2);
            End;
          Break;
        End;
      If K2 >= N Then
        Begin
          For i:=K1 to n do
            Begin
              k:=k+Pass(V1[i],1);
              Put(V1[i],b1);
              Inc(K1);
            End;
          Break;
        End;

      IF (V2[K2]>n) and (V1[K1]<=n) Then
        Begin
          k:=k+Pass(V1[K1],1);
          Put(V1[K1],b1);
          Inc(k1);
        End
      Else
        If (V1[K1]>n) and (V2[K2]<=n) Then
          Begin
            k:=k+Pass(V2[K2],2);
            Put(V2[K2],b1);
            Inc(k2);
          End
      Else
        If (V1[K1]>n) and (V2[K2]>n) Then
          Begin
            If (PassW(V1[K1],V2[K2],1) - Pass(V1[K1],1)) > (PassW(V2[K2],V1[K1],2) - Pass(V2[K2],2)) Then
              Begin
                k:=k+Pass(V1[K1],1);
                Put(V1[K1],b1);
                Inc(k1);
              End
            Else
              Begin
                k:=k+Pass(V2[K2],2);
                Put(V2[K2],b1);
                Inc(K2);
              End
          End
        Else
          Begin
            If (PassW(V1[K1],V2[K2],1) - Pass(V1[K1],1)) > (PassW(V2[K2],V1[K1],2) - Pass(V2[K2],2)) Then
              Begin
                k:=k+Pass(V1[K1],1);
                Put(V1[K1],b1);
                Inc(K1);
              End
            Else
              Begin
                k:=k+Pass(V2[K2],2);
                Put(V2[K2],b1);
                Inc(K2);
              End
          End;
    Until (K1>=n) and (K2>=n);
    End;

  WriteLn(k);
End.