program radu;
var p:longint;
    r,i:longint;
    f,g:text;
begin
     assign (f,'fact.in');
     reset (f);
     assign (g,'fact.out');
     rewrite (g);
     readln (f,p);
     r:=0;
     if (p+1) mod 6=0 then writeln (g,'-1')
                      else begin
     for i:=1 to p do
         if ((i+1) mod 6)<>0 then r:=r+5;
     writeln (g,r);
     end;
     close (f);
     close (g);
     end.