program xaudoixung_max;
uses crt;
var s,st,st2,st2:string;
i,j,k,max:byte;
begin
clrscr;
write('Nhap xau: '); readln(s);
st:=s[1]; max:=1;
for i:=1 to length(s)-1 do
begin
st2:=s[i];
for j:=i+1 to length(s) do
begin
st2:=st2+s[j];
if length(St2)>max then
begin
st3:='';
for k:=length(st2) downto 1 do
st3:=st3+st2[k];
if st2=st3 then
begin
max:=length(st2);
st:=st2;
end;
end;
end;
end;
write('Xau doi xung dai nhat la: ',st);
readln;
end.
