var f:text;
c:char;
flag:boolean;
cuv,lit,m:longint;
begin
assign(f,'text.in');
reset(f);
cuv:=0;
flag:=true;
lit:=0;
read(f,c);
if(eof(f)) then m:=-1;
while (not eof(f))do
begin
   if (not flag)and(c in ['a'..'z','A'..'Z']) then begin
                                                  flag:=true;
                                                  cuv:=cuv+1;
                                                  end;
   if c in ['a'..'z','A'..'Z'] then begin
                                    inc(lit);
                                    flag:=true;
                                    end
           else
                        flag:=false;
   read(f,c);
   if((eof(f)or eoln(f))and(flag=true)) then inc(cuv);
end;
close(f);
assign(f,'text.out');
rewrite(f);
if(cuv<>0) then begin
                m:=lit div cuv;
                write(f,m);
                end
           else
                write(f,0);
close(f);
end.