program fact;
 var a:array [1..50000]of longint;
     i,k1,k,n:longint;
     fi,fo:text;
begin assign(fi,'fact.in');
      assign(fo,'fact.out');
      reset(fi);
      rewrite(fo);
      read(fi,k);
      k1:=1;
      n:=1;
      repeat for i:=1 to k1 do n:=i*5;
            if k<=1 then k1:=k else inc(k1);
      until k<=k1;

      if k=0 then n:=1;
      write(fo,n);
      close(fo);
end.