static object Solve()
{
var n = int.Parse(Console.ReadLine());
var ps = Array.ConvertAll(new bool[n], _ => IntV.Parse(Console.ReadLine()));
var gs = ps.GroupBy(p => p.X).OrderBy(g => g.Key).Select(g => g.OrderBy(p => p.Y).ToArray()).ToArray();
var ps_u = GetUpper();
var ps_l = GetLower();
var area2 = GetArea2(ps_u) - GetArea2(ps_l);
var lattices = 0L;
lattices += gs[0][^ 1].Y - gs[0][0].Y;
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);
}
static object Solve()
{
var n = int.Parse(Console.ReadLine());
var ps = Array.ConvertAll(new bool[n], _ => IntV.Parse(Console.ReadLine()));
var r = 0;
for (int i = 0; i < n; i++)
{
for (int j = i + 1; j < n; j++)
{
for (int k = j + 1; k < n; k++)
{
var v1 = ps[i] - ps[j];
var v2 = ps[i] - ps[k];
if (!IntV.IsParallel(v1, v2))
{
r++;
}
}
}
}
return(r);
}
