var s, m, n, i, j: longint;
    u: boolean;

begin
 assign(input,'fact.in');
 reset(input);
 assign(output,'fact.out');
 rewrite(output);
 readln(m);
 n:=m*4+1;
 u:=false;
 j:=0;
 repeat
 inc(j);
  i:=1;
  s:=0;
 repeat
  i:=i*5;
  s:=s+(n div i);
 until (n div i)=0;

  if s=m then u:=true
         else inc(n);
  if j=6 then Begin n:=-1; u:=true; end;

 until u;

 writeln(n);

close(input);
close(output);
end.