#include <iostream> #include <vector> #include <algorithm> #include <cmath> #include <bitset> #include <queue> typedef long long ll; #define rep(i,n) for(int i = 0;i<n;++i) #define repc(bit,k,n) for (int bit = (1<<k)-1;bit < (1<<n); bit = next_combination(bit)) #define repi(itr,vec) for(auto itr = vec.begin();itr!=vec.end();++itr) using namespace std; using Graph = vector<vector<int> >; /* next combination * usage:repc(bit,k,n) * */ int next_combination(int sub) { int x = sub & -sub, y = sub + x; return (((sub & ~y) / x) >> 1) | y; } /* uniq * usage:uniq(vec) * */ void uniq(vector<int> &vec){ sort(vec.begin(), vec.end()); vec.erase(unique(vec.begin(), vec.end()), vec.end()); return; } int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); int n;cin>>n; vector<int> a(n),b(n); rep(i,n)cin>>a[i]; rep(i,n)cin>>b[i]; vector<int> v; rep(i,n)v.push_back(i); int ans = 0; int count = 0; do{ int win = 0; rep(i,n){ if(a[v[i]]>b[i])win++; } if(win*2>n)ans++; count++; }while(next_permutation(v.begin(),v.end())); cout << double(ans)/count << '\n'; return 0; }