uses crt;
var s:string[50];
i,dem:byte;
begin
clrscr;
write('Nhap s: '); readln(s);
for i:=1 to length(s) do
if ('a'<=s[i]) and ('z'>=s[i]) then inc(dem);
if dem=0 then write('Khong có ki tu nao là chu in thuong co trong xau');
write('So ky tu in thuong la: ',dem);
readln
end.