package no096;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.HashMap;
import java.util.NoSuchElementException;


public class Main {

	public static void main(String[] args) {
		IO io = new IO();
		int n = io.nextInt();
		if (n == 0) {
			System.out.println(1);
			return;
		}
		Vector2[] r = new Vector2[n];
		HashMap<Long, Integer> hm = new HashMap<>();
		for(int i=0;i<n;i++) {
			int x = io.nextInt();
			int y = io.nextInt();
			r[i] = new Vector2(x,y);
			hm.put(hash(x,y), i);
		}
		UnionFind uf = new UnionFind(n);
		for(int i=0;i<n;i++) {
			for(int x=-10;x<=10;x++) {
				for(int y=-10;y<=10;y++) {
					if (x * x + y * y > 100) {
						continue;
					}
					long hash = hash(r[i].x+x,r[i].y+y);
					if (hm.containsKey(hash)) {
						uf.union(i, hm.get(hash));
					}
				}
			}
		}
		long maxSq = 0;
		ArrayList<ArrayList<Integer>> groups = uf.groups();

		for(ArrayList<Integer> group:groups) {
			Vector2[] p = new Vector2[group.size()];
			for(int i=0;i<p.length;i++) {
				p[i] = r[group.get(i)];
			}
			ArrayList<Vector2> convex = new ArrayList<>();
			if (p.length <= 2) {
				convex = new ArrayList<>();
				for(int i=0;i<p.length;i++) {
					convex.add(p[i]);
				}
			}else{
				convex = Vector2.convexHull(p);
			}
			for(int i=0;i<convex.size();i++) {
				for(int j=i+1;j<convex.size();j++) {
					maxSq = Math.max(maxSq, convex.get(i).distSquare(convex.get(j)));
				}
			}
		}
		System.out.println(Math.sqrt(maxSq) + 2);
	}

	public static long hash(int x,int y) {
		return (x+10500)*30000+(y+10500);
	}

}
class Vector2 {
	int x = 0;
	int y = 0;
	public Vector2(int x,int y) {
		this.x = x;
		this.y = y;
	}
	public int dot(Vector2 v) {
		return this.x*v.x+this.y*v.y;
	}
	public int cross(Vector2 v) {
		return this.x*v.y-this.y*v.x;
	}
	public Vector2 add(Vector2 v) {
		return new Vector2(this.x+v.x,this.y+v.y);
	}
	public Vector2 subtract(Vector2 v) {
		return new Vector2(this.x-v.x,this.y-v.y);
	}
	public Vector2 multiply(int k) {
		return new Vector2(k*this.x,k*this.y);
	}
	public long normSquare() {
		return x * x + y * y;
	}
	public long distSquare(Vector2 v) {
		return this.subtract(v).normSquare();
	}
	public static boolean intersects(Vector2 p0,Vector2 p1,Vector2 p2,Vector2 p3) {
		Vector2 v1 = p1.subtract(p0);
		Vector2 v2 = p3.subtract(p2);
		Vector2 v = p2.subtract(p0);
		Vector2 v_ = p2.subtract(p1);
		int a = v1.cross(v2);
		if(a==0) {
			return v.cross(v_) == 0 && (v.dot(v_) <= 0 || p0.subtract(p2).dot(p0.subtract(p3)) <= 0);
		}else{
			int a1 = -v1.cross(v);
			int a2 = -v2.cross(v);
			if (a>0) {
				return (0<=a1&&a1<=a&&0<=a2&&a2<=a);
			}else{
				return (a<=a1&&a1<=0&&a<=a2&&a2<=0);
			}
		}
	}
	public static ArrayList<Vector2> convexHull(Vector2[] p) {
		int n = p.length;
		Arrays.sort(p,new LexicographicalComp());
		int k = 0;
		ArrayList<Vector2> q = new ArrayList<Vector2>();
		for(int i=0;i<n;i++) {
			while(k > 1 && q.get(k-1).subtract(q.get(k-2)).cross(p[i].subtract(q.get(k-1))) <= 0) {
				k--;
			}
			q.add(p[i]);
			k++;
		}
		for(int i=n-2, t=k;i>=0;i--) {
			while(k > t && q.get(k-1).subtract(q.get(k-2)).cross(p[i].subtract(q.get(k-1))) <= 0) {
				k--;
			}
			q.add(p[i]);
			k++;
		}
		return q;
	}
	public String toString() {
		return this.x + " " + this.y;
	}
	public static class LexicographicalComp implements Comparator<Vector2>{
		public int compare(Vector2 o1, Vector2 o2) {
			if (o1.x != o2.x) {
				return Integer.compare(o1.x, o2.x);
			}
			return Integer.compare(o1.y, o2.y);
		}
	}
}
class UnionFind {
	private int[] data;
	public UnionFind(int size) {
		data = new int[size];
		Arrays.fill(data, -1);
	}
	public void union(int x,int y) {
		x = root(x);
		y = root(y);
		if (x!=y) {
			if (data[y] < data[x]) {
				int tmp = y;
				y = x;
				x = tmp;
			}
			data[x] += data[y];
			data[y] = x;
		}
	}
	public boolean isConnected(int x,int y) {
		return root(x)==root(y);
	}
	private int root(int x) {
		return data[x] < 0 ? x : (data[x] = root(data[x]));
	}
	public int size(int x) {
		return -data[root(x)];
	}
	public ArrayList<ArrayList<Integer>> groups() {
		int n = data.length;
		ArrayList<ArrayList<Integer>> g = new ArrayList<ArrayList<Integer>>();
		HashMap<Integer,Integer> hm = new HashMap<Integer, Integer>();
		for(int i=0;i<n;i++) {
			int r = root(i);
			if (!hm.containsKey(r)) {
				hm.put(r, g.size());
				g.add(new ArrayList<Integer>());

			}
			g.get(hm.get(r)).add(i);
		}
		return g;
	}
	public String toString() {
		return Arrays.toString(data);
	}
}

class IO {
	private final InputStream in;
	private final PrintWriter out = new PrintWriter(System.out);
	private final byte[] buffer = new byte[1024];
	private int ptr = 0;
	private int buflen = 0;

	public IO() { this(System.in);}
	public IO(InputStream source) { this.in = source;}
	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		}else{
			ptr = 0;
			try {
				buflen = in.read(buffer);
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (buflen <= 0) {
				return false;
			}
		}
		return true;
	}
	private int readByte() { if (hasNextByte()) return buffer[ptr++]; else return -1;}
	private static boolean isPrintableChar(int c) { return 33 <= c && c <= 126;}
	private static boolean isNewLine(int c) { return c == '\n' || c == '\r';}
	private void skipUnprintable() { while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;}
	private void skipNewLine() { while(hasNextByte() && isNewLine(buffer[ptr])) ptr++;}
	public boolean hasNext() { skipUnprintable(); return hasNextByte();}
	public boolean hasNextLine() { skipNewLine(); return hasNextByte();}
	public String next() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while(isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	public String nextLine() {
		if (!hasNextLine()) {
			throw new NoSuchElementException();
		}
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while(!isNewLine(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	public long nextLong() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		while(true){
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			}else{
				return minus ? -n : n;
			}
			b = readByte();
		}
	}
	public int nextInt() {
		long nl = nextLong();
		if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE) {
			throw new NumberFormatException();
		}
		return (int) nl;
	}
	public char nextChar() {
		if (!hasNext()) {
			throw new NoSuchElementException();
		}
		return (char) readByte();
	}
	public double nextDouble() { return Double.parseDouble(next());}
	public int[] arrayInt(int n) { int[] a = new int[n]; for(int i=0;i<n;i++) a[i] = nextInt(); return a;};
	public long[] arrayLong(int n) { long[] a = new long[n]; for(int i=0;i<n;i++) a[i] = nextLong(); return a;};
	public double[] arrayDouble(int n) { double[] a = new double[n]; for(int i=0;i<n;i++) a[i] = nextDouble(); return a;};
	public void arrayInt(int[]... a) {
		for(int i=0;i<a[0].length;i++) {
			for(int j=0;j<a.length;j++) {
				a[j][i] = nextInt();
			}
		}
	}
	public void println(long x) { out.println(x);}
	public void println(double x) { out.println(x);}
	public void println(String s) { out.println(s);}
	public void println() { out.println(); }
	public void print(long x) { out.print(x); }
	public void print(double x) { out.print(x); }
	public void print(String s) { out.print(s); }
	public void print(char c) {out.print(c);}
	public void flush() {out.flush(); }
}