program xoachucai;
uses crt;
var st:string;
i:byte;
begin
clrscr;
write('Nhap xau: '); readln(st);
i:=1;
while i<=length(st) do
if (st[i] in ['a'..'z']) or (st[i] in ['A'..'Z']) then delete(st,i,1)
else inc(i);
write('Xau sau khi xoa chu cai la: ',st);
readln
end.