#include using namespace std; using uint = unsigned int; using ll = long long; using ull = unsigned long long; template using V = vector; template using VV = V>; template using VVV = V>; template using VVVV = VV>; #define rep(i,n) for(ll i=0ll;i void chmin(T& t, const U& u) { if (t > u) t = u; } template void chmax(T& t, const U& u) { if (t < u) t = u; } // cin.tie(nullptr); // ios::sync_with_stdio(false); // cout << fixed << setprecision(20); void solve(){ ll n; cin >> n; V a(n), b(n); rep(i,n) cin >> a[i]; rep(i,n) cin >> b[i]; sort(be(a)); sort(be(b)); ll ans = 0; ll cnt = 0; do{ cnt ++; ll cc = 0; rep(i, n){ if(a[i] < b[i]) cc--; if(a[i] > b[i]) cc++; } if(cc>0) ans++; }while(next_permutation(be(a))); cout << fixed << setprecision(20); cout << 1.0*ans/cnt << endl; } int main(){ cin.tie(nullptr); ios::sync_with_stdio(false); int t=1; // cin >> t; rep(i,t) solve(); }