var f,g:text;
    p,a,c,b:longint;
function nro(x:longint):longint;
var z,nr:longint;
begin
     z:=5; nr:=0;
     while x div z<>0 do
     begin
          nr:=nr+x div z;
          z:=z*5;
     end;
     nro:=nr;
end;
begin
     assign(f,'factorial.in'); reset(f);
     assign(g,'factorial.out'); rewrite(g);
     readln(f,p);
     a:=0;
     b:=1500000000;
     if p=0 then writeln(g,'1');
     if p>0 then
     begin
          repeat
               c:=(a+b)div 2;
               if nro(c)>p then a:=c+1;
               if nro(c)<p then b:=c-1;
          until nro(c)=p;
          while c mod 5 <>0 do dec(c);
          writeln(g,c);
     end;
     close(g);
end.