import java.util.*;
import java.io.*;

class P{
	double x, y;
	public P(double x, double y) {
		super();
		this.x = x;
		this.y = y;
	}
}

public class Main {
	static final int mod = (int) 1e9 + 7;
	static final int DX[] = { -1, 0, 1, 0 }, DY[] = { 0, -1, 0, 1 };
	static final int[] DX8 = { -1, -1, -1, 0, 0, 1, 1, 1 }, DY8 = { -1, 0, 1, -1, 1, -1, 0, 1 };
	static final int INF = Integer.MAX_VALUE / 3;
	static final long LINF = Long.MAX_VALUE / 3;
	static final String nextLine = "\n";

	static int n;
	static P ps[];
	
	public static void main(String[] args) {
		FastScanner fs = new FastScanner(System.in);
		n = fs.nextInt();
		ps = new P[n];
		for(int i=0;i<n;i++) {
			int x = fs.nextInt(), y = fs.nextInt();
			ps[i] = new P(x,y);
		}
		double l = 0, r = 1000;
		for(int i=0;i<100;i++) {
			double c1 = (l * 2 + r)/3, c2 = (l + r * 2)/3;
			if(f(c1)>f(c2))l = c1; else r = c2;
		}
		System.out.println(f(l));
	}
	
	//xを固定した時の、最遠点までの距離
	static double f(double x) {
		double l = 0, r = 1000;
		for(int i=0;i<100;i++) {
			double c1 = (l * 2 + r)/3, c2 = (l + r * 2)/3;
			if(g(x, c1)>g(x, c2))l = c1; else r = c2;
		}
		return g(x, l);
	}

	//最遠点への距離を返す
	static double g(double x, double y) {
		double max = 0;
		for(int i=0;i<n;i++) {
			max = Math.max(max,(x - ps[i].x)*(x - ps[i].x) + (y - ps[i].y)*(y - ps[i].y) );
		}
		return Math.sqrt(max);
	}
	
	//MOD culculations
	static long plus(long x, long y) {
		long res = (x + y) % mod;
		return res < 0 ? res + mod : res;
	}

	static long sub(long x, long y) {
		long res = (x - y) % mod;
		return res < 0 ? res + mod : res;
	}

	static long mul(long x, long y) {
		long res = (x * y) % mod;
		return res < 0 ? res + mod : res;
	}

	static long div(long x, long y) {
		long res = x * pow(y, mod - 2) % mod;
		return res < 0 ? res + mod : res;
	}

	static long pow(long x, long y) {
		if (y < 0)
			return 0;
		if (y == 0)
			return 1;
		if (y % 2 == 1)
			return (x * pow(x, y - 1)) % mod;
		long root = pow(x, y / 2);
		return root * root % mod;
	}
}

//高速なScanner
class FastScanner {
	private BufferedReader reader = null;
	private StringTokenizer tokenizer = null;

	public FastScanner(InputStream in) {
		reader = new BufferedReader(new InputStreamReader(in));
		tokenizer = null;
	}

	public String next() {
		if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				tokenizer = new StringTokenizer(reader.readLine());
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken();
	}

	public String nextLine() {
		if (tokenizer == null || !tokenizer.hasMoreTokens()) {
			try {
				return reader.readLine();
			} catch (IOException e) {
				throw new RuntimeException(e);
			}
		}
		return tokenizer.nextToken("\n");
	}

	public long nextLong() {
		return Long.parseLong(next());
	}

	public int nextInt() {
		return Integer.parseInt(next());
	}

	public double nextDouble() {
		return Double.parseDouble(next());
	}

	public int[] nextIntArray(int n) {
		int[] a = new int[n];
		for (int i = 0; i < n; i++)
			a[i] = nextInt();
		return a;
	}

	public long[] nextLongArray(int n) {
		long[] a = new long[n];
		for (int i = 0; i < n; i++)
			a[i] = nextLong();
		return a;
	}
}

Measured memory_bytes: 21204