import java.util.*; public class Main { static int[] par; static int[] rank; public static void main(String[] args) { Scanner sc = new Scanner(System.in); int n = sc.nextInt(); par = new int[n]; rank = new int[n]; long[] x = new long[n]; long[] y = new long[n]; init(n); for(int i = 0; i < n; i++) { x[i] = sc.nextLong(); y[i] = sc.nextLong(); } for(int i = 0; i < n - 1; i++) { for(int j = i + 1; j < n; j++) { if(((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j])) <= 100) unite(i, j); } } double ans = 0; for(int i = 0; i < n - 1; i++) { for(int j = i + 1; j < n; j++) { if(same(i, j)) ans = Math.max(ans, Math.sqrt(((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j])))); } } ans += 2; System.out.println(ans); } static void init(int m) { for(int i = 0; i < m; i++) { par[i] = i; rank[i] = 0; } } static int find(int x) { if(par[x] == x) { return x; } else { return par[x] = find(par[x]); } } static void unite(int x, int y) { x = find(x); y = find(y); if(x != y) { if(rank[x] < rank[y]) { par[x] = y; } else { par[y] = x; if(rank[x] == rank[y]) { rank[x]++; } } } } static boolean same(int x, int y) { return find(x) == find(y); } }