Câu trả lời:
program bai1;
uses crt;
var i:integer;
s,s1:string;
begin
clrscr;
write('nhap S:');readln(s);
while pos('C',s)<>0 do
begin
insert('LOP11A',s,pos('C',s));
delete(s,pos('C',s),1);
end;
writeln('xau sau khi bien doi la: ',s);
writeln('do dai cua xau tren la: ',length(s));
write('nhap s1:');readln(s1);
if s1[1]=s[1] then writeln('ki tu dau cua hai xau trung nhau')
else writeln('ki tu dau cua hai xau khong trung nhau');
readln;
end.