Pascal :

var str:ansistring;
    n,i,j,sum,ans:longint;
begin
  
  readln(n);
  readln(str);
  str:=str+str+str;
  ans:=0;
  for i:=n+1 to n+n do
  begin
    sum:=0;
    for j:=i downto 1 do
      if (str[i]=str[j]) or (str[j]='w') then
        else break;
    sum:=i-j;
    for j:=i+1 to n+n+n do
      if (str[i]=str[j]) or (str[j]='w') then
        else break;
    sum:=sum+j-i;
    if sum>ans then ans:=sum;
  end;
  writeln(ans);
  
end.