Const z=1000000;
Var i,n:integer;
a,e:int64;
d:array [-z..z] of Int64;
s:array [1..z] of char;
begin
  reset(input,'input.txt');
  Assign(output,'output.txt');
  Readln(n);
  for i:=1 to n do
  read(s[i]);
  d[0]:=1;
  for i:=1 to n do
  begin
    if s[i]='a'
    then inc(a)
    else dec(a);
    e:=e+d[a];
    inc(d[a])
  end;
  Write(e)
end.