import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); int N = scanner.nextInt(); int[] X = new int[N]; int[] Y = new int[N]; if (N == 0) { System.out.println(1); return; } for (int i = 0; i < N; i++) { X[i] = scanner.nextInt(); Y[i] = scanner.nextInt(); } UnionFind union = new UnionFind(N); for (int i = 0; i < N; i++) { for (int j = i + 1; j < N; j++) { if (Math.hypot(X[i] - X[j], Y[i] - Y[j]) <= 10) { union.union(i, j); } } } double mx = 0; for (int i = 0; i < N; i++) { for (int j = i + 1; j < N; j++) { if (union.same(i, j)) { double len = Math.hypot(X[i] - X[j], Y[i] - Y[j]); if (mx < len) { mx = len; } } } } System.out.println(mx + 2); } } class UnionFind { int[] parent; int[] rank; public UnionFind(int N) { parent = new int[N]; rank = new int[N]; for (int i = 0; i < N; i++) { parent[i] = i; } } public int find(int A) { if (parent[A] == A) { return A; } return find(parent[A]); } public boolean same(int A, int B) { return find(A) == find(B); } public void union(int A, int B) { int Aroot = find(A); int Broot = find(B); if (rank[Aroot] > rank[Broot]) { parent[Broot] = Aroot; } else if (rank[Aroot] < rank[Broot]) { parent[Aroot] = Broot; } else if (Aroot != Broot) { parent[Aroot] = Broot; rank[Broot]++; } } }