var f:text;
    k,i,n,p:longint;

begin
 assign(f,'fact.in');
 reset(f);
 readln(f,p);
 close(f);
 if p=0 then begin
  i:=6;
 end
 else begin
 k:=0;
 i:=5;
 while k<p do
 begin
  n:=i;
  while n mod 5=0 do begin
   inc(k);
   n:=n div 5;
  end;
  inc(i,5);
 end;
 end;
 assign(f,'fact.out');
 rewrite(f);
 writeln(f,i-5);
 close(f);
end.