Program HOC24;
var i,d1,d2: byte;
st1,st2: string[60];
begin
write('Nhap xau st1: '); readln(st1);
//---------------Câu 1-------------------
d1:=0; d2:=0;
for i:=1 to length(st1) do
begin
if st1[i]='A' then d1:=d1+1;
if st1[i]='a' then d2:=d2+1;
end;
writeln('Co ',d1,' ki tu A trong xau');
writeln('Co ',d2,' ki tu a trong xau');
//---------------------- Câu 2 --------------------
st2:=''
for i:=1 to length(st1) do if st1[i] in ['a'..'z'] then st2:=st2+st1[i];
writeln('Xau st2 la: ',st2);
//------------------------------Câu 3--------------------
for i:=1 to length(st1) do st1[i]:=upcase(st1[i]);
write('Xau st1 sau khi in hoa la: ',st1);
//--------------------------------------------------------
readln
end.