var
 n,b,i,l,c,cc:longint;
 a:array[1..10000000] of longint;
begin
  readln(n);
  for i:=1 to n do read(a[i]);
  l:=0; b:=0; i:=0;
  repeat
  inc(i);
  if a[i]>l then begin b:=b+(a[i]-l)*6+6; l:=a[i]; end;
 if a[i]<l then begin  b:=b+(l-a[i])*4+6; l:=a[i]; end;
  for c:=i+1 to n do if a[c]=a[i] then
  begin
  b:=b+1;
  for  cc:=c to n do a[cc]:=a[cc+1];
  n:=n-1;
  end;
  until i=n;
  b:=b+l*4;
  writeln(b);
end.