#include <bits/stdc++.h> //#include <atcoder/all> #define rep(i, n) for (int i = 0; i < (n); i++) using ll = long long; using namespace std; //using namespace atcoder; const int mod = 1e7+7; const int INF =1e9+1; int n; vector<int> a,b; vector<bool> flag1,flag2; int win=0, match=0; void dfs(vector<int> x,vector<int> y){ if(x.size()==n){ match++; int tmp1=0,tmp2=0; rep(i,n){ if(x[i]>y[i])tmp1++; else if(x[i]<y[i])tmp2++; } if(tmp1>tmp2)win++; return ; } for(int i=0;i<n;i++){ if(flag1[i]==1)continue; x.push_back(a[i]);flag1[i]=1; rep(j,n){ if(flag2[j]==1)continue; y.push_back(b[j]);flag2[j]=1; dfs(x,y); y.pop_back();flag2[j]=0; } x.pop_back(); flag1[i]=0; } } int main() { cin>>n; a=b=vector<int> (n); flag1=flag2=vector<bool>(n,0); rep(i,n)cin>>a[i]; rep(i,n)cin>>b[i]; dfs(vector<int>(0),vector<int>(0)); cout<<fixed<<setprecision(15); cout<<(double)win/match<<endl; }