var a:char;
    f:text;
    ltotal,nrcuv:longint;
begin
assign(f,'text.in');
reset(f);
ltotal:=0;
nrcuv:=0;
while not eof(f) do
begin read(f,a);
      While  (ord(a)<64) or (ord(a)>122) or((ord(a)>90) and (ord(a)<97)) do
                 read(f,a);
      while ((ord(a)>64) and (ord(a)<91)) or ((ord(a)>96) and (ord(a)<123)) do
       begin inc(ltotal);
             read(f,a);
       end;
        inc(nrcuv);
end;
close(f);
assign(f,'text.out');
rewrite(f);
write(f,ltotal div nrcuv);
close(f);
end.