Работа с типом днных STRING

[danekne]

program Untitled;
uses crt;
var
   f:text;
   s:string;
   i:integer;
begin
   //assign(f,'file.txt');
   //reset(f);
   //while not eof(f) do
        // begin
writeln('вводите строку');            
readln(s);
            for i:=1 to length(s) do
                begin
                     if (s[i]>='0') and(s[i]<='9') then
                     begin
                      break;
                     end
                     else
                     begin
                       if i=length(s) then
                          begin
                          writeln(s);
                          end;
                     end;
                end;
         end;
   //close(f);
   readkey;
end.