Watering the Fields

Farmer John needs an irrigation system between his N fields (1 ≤ N ≤ 2000) during a drought.

Field i is a distinct point (xi, yi) with 0 ≤ xi, yi ≤ 1000. A pipe between fields i and j costs the squared Euclidean distance:

(xi - xj)^2 + (yi - yj)^2

Build a minimum-cost network of pipes so every field can reach every other field through pipes.

The contractor installs a pipe only if its cost is at least C (1 ≤ C ≤ 1,000,000). Output the minimum total cost, or -1 if no such network exists.

• Line 1: integers N and C
• Lines 2 through N+1: integers xi and yi for each field

• Line 1: the minimum cost to connect all fields, or -1 if impossible