static object Solve()
{
var n = int.Parse(Console.ReadLine());
var ps = Array.ConvertAll(new bool[n], _ => IntV.Parse(Console.ReadLine()));
var r = 0;
IntV tp = (1L, 0L);
foreach (var p in ps.OrderBy(p => p - IntV.UnitX))
{
if (tp.CompareTo(p - IntV.UnitY) <= 0)
{
r++;
tp = p - IntV.UnitX;
}
}
return(r);
}
