#include <stdio.h>
#include <stdlib.h>

int getrand(int min, int max) {
	return min + (int)(rand() * (max - min + 1.0) / (1.0 + RAND_MAX));
}

void swap(int *a, int *b) {
	int tmp = *a;
	*a = *b;
	*b = tmp;
}

void shuffle(int *d, int size) {
	int tmp1 = getrand(0, size - 1);
	int tmp2 = getrand(0, size - 1);
	swap(&d[tmp1], &d[tmp2]);
}

int main() {
	int n;
	scanf("%d", &n);

	int a[4], b[4];
	int i, j;
	for (i = 0; i < n; i++) scanf("%d", &a[i]);
	for (i = 0; i < n; i++) scanf("%d", &b[i]);

	int cnta = 0, num = 300;
	for (i = 0; i < num; i++) {
		shuffle(a, n);
		shuffle(b, n);
		int cnt = 0;
		for (j = 0; j < n; j++) {
			if (a[j] > b[j]) cnt++;
		}
		if (cnt > n / 2) cnta++;
	}

	printf("%.3lf\n", (double)cnta / num);
	return 0;
}