Bài giả CLB Tin học kì 3

Program KTDX;
Var s,s1:string;
f1,f2:text;
Function KT(s:string):boolean;
Var t,j:integer;
Begin
t:=length(s);
For j:=1 to length(s) do
If s[j]=s[t] then
Begin
dec(t);
kt:=true;
End
Else
Begin
kt:=false;
break;
End;
End;
Procedure docfile;
Begin
s:='';
assign(f1,'doixung.inp');
reset(f1);
assign(f2,'doixung.out');
rewrite(f2);
While not eof(f1) do
Begin
While not eoln(f1) do
Begin
read(f1,s1);
s:=s+s1;
End;
readln(f1);
If kt(s)=true then writeln(f2,'YES')
Else writeln(f2,'NO');
s:='';
End;
close(f2);
End;
Begin
docfile;
End.