import java.util.*;


public class Main_yukicoder94 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int n = sc.nextInt();

        int[] x = new int[n];
        int[] y = new int[n];
        for (int i = 0; i < n; i++) {
        	x[i] = sc.nextInt();
        	y[i] = sc.nextInt();
        }

		UnionFind uf = new UnionFind(n);
		int[][] dis = new int[n][n];

		for (int i = 0; i < n; i++) {
			for (int j = i + 1; j < n; j++) {
				dis[i][j] = (x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j]);
				if (dis[i][j] <= 100) {
					uf.union(i, j);
				}
			}
		}

		int max = 0;
		for (int i = 0; i < n; i++) {
			for (int j = i + 1; j < n; j++) {
				if (uf.same(i, j)) {
					max = Math.max(max, dis[i][j]);
				}
			}
		}

		if (n == 0) {
			System.out.println(1);
		} else {
			System.out.printf("%.7f\n", Math.sqrt(max) + 2);
		}

        sc.close();
    }

	@SuppressWarnings("unused")
	private static class UnionFind {
		int[] parent;
		int[] rank;

		UnionFind(int n) {
			parent = new int[n];
			rank = new int[n];
			for (int i = 0; i < n; i++) {
				parent[i] = i;
				rank[i] = 0;
			}
		}

		int find(int x) {
			if (parent[x] == x) {
				return x;
			} else {
				return parent[x] = find(parent[x]);
			}
		}

		boolean same(int x, int y) {
			return find(x) == find(y);
		}

		void union(int x, int y) {
			x = find(x);
			y = find(y);
			if (x != y) {
				if (rank[x] > rank[y]) {
					parent[y] = x;
				} else {
					parent[x] = y;
					if (rank[x] == rank[y]) {
						rank[y]++;
					}
				}
			}

			return;
		}

		// 異なる集合の数
		int count() {
			int ret = 0;
			for (int i = 0; i < parent.length; i++) {
				if (find(i) == i) {
					ret++;
				}
			}

			return ret;
		}
	}
}