#include <cstdio>
#include <cmath>
int n;
long double x[1005], y[1005], X, Y, d, e;
long double dist(double a, double b) {
    return a*a + b*b;
}
int main() {
    int ggg=scanf("%d", &n);
    for (int i = 0; i < n; i++) {
        int gg=scanf("%Lf %Lf", &x[i], &y[i]);
        X += x[i]; Y += y[i];
    }
    X /= n; Y /= n;
    double P = 0.1;
    for (int i = 0; i < 300000; i++) {
        int f = 0;
        d = dist(X - x[0], Y - y[0]);
        for (int j = 1; j < n; j++) {
            e = dist(X - x[j], Y - y[j]);
            if (d < e) { d = e; f = j; }
        }
        X += (x[f] - X)*P;
        Y += (y[f] - Y)*P;
        P *= 0.999;
    }
    printf("%.6Lf", sqrtl(d));
}
