#include using namespace std; typedef long long signed int LL; typedef long long unsigned int LU; #define incID(i, l, r) for(int i = (l) ; i < (r); i++) #define incII(i, l, r) for(int i = (l) ; i <= (r); i++) #define decID(i, l, r) for(int i = (r) - 1; i >= (l); i--) #define decII(i, l, r) for(int i = (r) ; i >= (l); i--) #define inc(i, n) incID(i, 0, n) #define inc1(i, n) incII(i, 1, n) #define dec(i, n) decID(i, 0, n) #define dec1(i, n) decII(i, 1, n) #define inII(v, l, r) ((l) <= (v) && (v) <= (r)) #define inID(v, l, r) ((l) <= (v) && (v) < (r)) #define PB push_back #define EB emplace_back #define MP make_pair #define FI first #define SE second #define UB upper_bound #define LB lower_bound #define PQ priority_queue #define ALL(v) v.begin(), v.end() #define RALL(v) v.rbegin(), v.rend() #define FOR(it, v) for(auto it = v.begin(); it != v.end(); ++it) #define RFOR(it, v) for(auto it = v.rbegin(); it != v.rend(); ++it) template bool setmin(T & a, T b) { if(b < a) { a = b; return true; } else { return false; } } template bool setmax(T & a, T b) { if(b > a) { a = b; return true; } else { return false; } } template bool setmineq(T & a, T b) { if(b <= a) { a = b; return true; } else { return false; } } template bool setmaxeq(T & a, T b) { if(b >= a) { a = b; return true; } else { return false; } } template T gcd(T a, T b) { return (b == 0 ? a : gcd(b, a % b)); } template T lcm(T a, T b) { return a / gcd(a, b) * b; } // ---- ---- #include typedef long long unsigned int LLUI; class Permutation { public: Permutation(int size); LLUI get_counter(); int get_at(int n); void set_permutation(LLUI n); bool next_permutation(); bool previous_permutation(); private: int size; int a[20]; LLUI counter; LLUI frac(LLUI n) { if(n == 0) { return 1; } return n * frac(n - 1); } void swap(int i, int j) { int temp = a[i]; a[i] = a[j]; a[j] = temp; } void reverse(int i, int j) { // 閉区間 for(int k = i, l = j; k < l; k++, l--) { swap(k, l); } } }; Permutation::Permutation(int size) { counter = 0; for(int i = 0; i < size; i++) { a[i] = i; } this -> size = size; } LLUI Permutation::get_counter() { return counter; } int Permutation::get_at(int n) { return a[n]; } void Permutation::set_permutation(LLUI n) { counter = n; LLUI f[20]; bool enable[20]; f[0] = 1; for(int i = 1; i < size; i++) { f[i] = f[i - 1] * i; enable[i] = true; } for(int i = size - 1; 0 <= i; i--) { int p = n / f[i], c = 0, j = 0; while(true) { c += (enable[j] ? 1 : 0); if(c == p + 1) { break; } j++; } enable[j] = false; a[size - 1 - i] = j; n %= f[i]; } return; } bool Permutation::next_permutation() { for(int i = size - 2; 0 <= i; i--) { if(a[i] < a[i + 1]) { int j = size - 1; while(a[i] > a[j]) { j--; } swap(i, j); reverse(i + 1, size - 1); counter++; return true; } } reverse(0, size - 1); counter = 0; return false; } bool Permutation::previous_permutation() { for(int i = size - 2; 0 <= i; i--) { if(a[i] > a[i + 1]) { int j = size - 1; while(a[i] < a[j]) { j--; } swap(i, j); reverse(i + 1, size - 1); counter--; return true; } } reverse(0, size - 1); counter = frac(size) - 1; return false; } // ---- ---- int n, a[4], b[4]; int main() { cin >> n; inc(i, n) { cin >> a[i]; } inc(i, n) { cin >> b[i]; } Permutation p(n); int t = 0, q = 0; do { int c = 0; inc(i, n) { if(a[i] > b[p.get_at(i)]) { c++; } else { c--; } } t++; if(c > 0) { q++; } } while(p.next_permutation()); printf("%.4f\n", 1.0 * q / t); return 0; }