program cel;
var f,g:text;
    n,p,fact,r:longint;
Begin
Assign(f,'fact.in');Reset(f);
Assign(g,'fact.out');Rewrite(g);
Read(f,p);
n:=0;
fact:=0;
While p>n do
 Begin
  inc(fact,5);
  If fact mod 25=0 then Begin
                         r:=fact;
                         If (r div 25) mod 5=0 then While r mod 5=0 do
                                                     Begin
                                                      r:=r div 5;
                                                      inc(n);
                                                     end
                                                else inc(n,2);
                        end
                   else inc(n,1);
 end;
If n=0 then Write(g,1)
       else Write(g,fact);
Close(f);
Close(g);
end.