ac1129.pas

某牛人写的acm.tongji.edu.cn上大部分ac的代码,仅供学习研究,请不要用来作弊

program tju1129;
var
  n:longint;
function count(x:longint):longint;
  var
    y:longint;
    s:string;
  begin
    if x<10 then
      count:=x+ord(x<7)
    else begin
      y:=x div 10-1;
      str(y+1,s);
      count:=count(y)*9+ord(pos('7',s)=0)*count(x mod 10);
    end;
  end;
begin
  repeat
    read(n);
    writeln(count(n)-1);
  until seekeof;
end.