var n,i,k,j,p:longint;
s:set of char;
a:array[1..1024] of char;
f,g:text;
c:char;
begin
for c:='a' to 'z' do s:=s+[c];
assign(f,'text.in');
reset(f);
while not eof(f) do begin
read(f,c);
c:=lowercase(c);
if c=' ' then p:=p+1;
if c in s then k:=k+1;
end;
p:=p+1;
close(f);
assign(g,'text.out');
rewrite(g);
writeln(g,k div p);
close(g);

end.