Var f,g:text;
    nrlit,nrcuv,i,i2:longint;
    a,v:char;

Begin
assign(f, 'text.in');reset(f);
assign(g, 'text.out');rewrite(g);
while eof(f)=false do
  begin
    read(f, a);
    case a of
      'a'..'z','A'..'Z':inc(nrlit);
     else inc(i2);
    end;
    case v of
      'a'..'z','A'..'Z':inc(i);
    end;
    if (i=1) and (i2=1) then inc(nrcuv);
    v:=a;
    i:=0;
    i2:=0;
  end;
write(g, nrlit div nrcuv);
close(f);
close(g);
End.