import std.stdio, std.conv, std.functional, std.string;
import std.algorithm, std.array, std.container, std.range, std.typecons;
import std.bigint, std.numeric, std.math, std.random;
import core.bitop;

string FMT_F = "%.10f";

static File _f;
void file_io(string fn) { _f = File(fn, "r"); }
static string[] s_rd;
T _RD(T = long)() { while(!s_rd.length) s_rd = readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; }
T _RD(T = long)(File f) { while(!s_rd.length) s_rd = f.readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; }
T[] _RDA(T = long)(T fix = 0) { auto r = readln.chomp.split.to!(T[]); r[] += fix; return r; }
T[] _RDA(T = long)(File f, T fix = 0) { auto r = f.readln.chomp.split.to!(T[]); r[] += fix; return r; }
T RD(T = long)() { if (_f.isOpen) return _RD!T(_f); else return _RD!T; }
T[] RDA(T = long)(T fix = 0) { if (_f.isOpen)  return _RDA!T(_f, fix); else return _RDA!T(fix); }

size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;}
size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; }

void chmin(T)(ref T x, T y) { x = min(x, y); } void chmax(T)(ref T x, T y) { x = max(x, y); }
bool inside(T)(T x, T b, T e) { return x >= b && x < e; }
long lcm(long x, long y) { return x * (y / gcd(x, y)); }

long mod = 10^^9 + 7;
//long mod = 998244353;
//long mod = 1_000_003;
void moda(ref long x, long y) { x = (x + y) % mod; }
void mods(ref long x, long y) { x = ((x + mod) - (y % mod)) % mod; }
void modm(ref long x, long y) { x = (x * y) % mod; }
void modpow(ref long x, long y) { if (!y) { x = 1; return; } auto t = x; x.modpow(y>>1); x.modm(x); if (y&1) x.modm(t); }

void main()
{
	auto N = RD;
	auto xy = new long[][](N);
	foreach (i; 0..N)
	{
		xy[i] = [RD, RD];
	}

	double f(double cx, double cy)
	{
		double res = 0.0;
		foreach (i; 0..N)
		{
			auto dx = cast(double)xy[i][0] - cx;
			auto dy = cast(double)xy[i][1] - cy;
			auto r2 = dx^^2 + dy^^2;
			res.chmax(r2);
		}
		return res;
	}

	double lx = 0.0, rx = 1000.0;
	double ly = 0.0, ry = 1000.0;
    foreach (i; 0..10^^6)
	{
		double rangeX = (rx - lx) / 20.0;
		double rangeY = (ry - ly) / 20.0;
        double x1 = lx + rangeX;
        double x2 = rx - rangeX;
		double y1 = ly + rangeY;
        double y2 = ry - rangeY;

		auto lt = f(x1, y1);
		auto rt = f(x2, y1);
		auto lb = f(x1, y2);
		auto rb = f(x2, y2);
		auto r = min(lt, rt, lb, rb);
        if (r == lt)
		{
			rx = x2;
			ry = y2;
		}
		else if (r == rt)
		{
			lx = x1;
			ry = y2;
		}
		else if (r == lb)
		{
			rx = x2;
			ly = y1;
		}
		else
		{
			lx = x1;
			ly = y1;
		}
		/*debug writef(FMT_F, lx);
		debug write(" ");
		debug writef(FMT_F, rx);
		debug write(" ");
		debug writef(FMT_F, ly);
		debug write(" ");
		debug writefln(FMT_F, ry);*/
    }
	auto ans = sqrt(f(lx, ly));

	writefln(FMT_F, ans);
	stdout.flush;
	debug readln;
}
