program barman;
  const
    fin='barman.in';
    fout='barman.out';
    nmax=600;
  var
    aa,a,at,obt:array[1..nmax] of longint;
    min:longint;
    i,j,x,y,n,k,next,vnext:longint;
begin
  assign(input,fin);
    reset(input);
    readln(n);
    for i:=1 to n do
      read(a[i]);
  close(input);
  assign(output,fout);
    rewrite(output);
    aa:=a;
    for i:=1 to n-1 do
      for j:=i+1 to n do
        if aa[i]>aa[j] then
          begin
            x:=aa[i];aa[i]:=aa[j];aa[j]:=x;
          end;
    at:=a;
    min:=maxlongint;
    for i:=1 to n do
      begin
        for j:=i to n do
          obt[j-i+1]:=aa[j];
        for j:=1 to i-1 do
          obt[n-i+1+j]:=aa[j];
        a:=at;
        x:=0;
        for j:=1 to n do
          if a[j]<>obt[j] then
            begin
              next:=j;
              vnext:=a[j];
              break;
            end;
        while vnext<>0 do
          begin
            k:=next;
            inc(x,10);
            repeat
              inc(k);
              if k=n+1 then k:=1;
            until (a[k]<>obt[k])and(obt[k]=vnext);
            y:=k;
            k:=next;
            repeat
              dec(k);
              if k=0 then k:=n;
            until (a[k]<>obt[k])and(obt[k]=vnext);
            if abs(y-next)<abs(k-next) then
              k:=y;
            inc(x,abs(next-k));
            inc(x,10);
            vnext:=a[k];
            a[k]:=a[next];
            a[next]:=0;
            next:=k;
          end;
        if x<min then
          min:=x;
      end;
    writeln(min);
  close(output);
end.