uses crt; var s:string; i:byte; begin clrscr; write('Nhap xau: '); readln(s); for i:=1 to length(s) do if (s[i]>='0') and (s[i]<='9') then write(s[i]); readln end.
uses crt; var s:string; i:byte; begin clrscr; write('Nhap s: '); readln(s); for i:=1 to length(s) do if (s[i]>='0') and (s[i]<='9') then write(s[i]); readln end.
