Bai 2 bai thuc hanh 5

program demchuoi;
var s: string;
dem: array[`A`..`Z`] of integer;
i: integer;
ch: char;
begin
write(`Nhap chuoi: `);readln(s);
for i:=1 to length(s) do
dem[upcase(s[i])]:= dem[upcase(s[i])]+1;
writeln;
writeln(`Cac ki tu trong chuoi la: `);
for ch:=`A`to `Z`do
if dem[ch]>0 then
writeln(`Chu: `,ch,` xuat hien `,dem[ch],`lan`);
writeln;
readln
end.