#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<n; i++)
//long long mo = 1e9 + 7;
int N;
int solve(int flagA, int flagB, int n, int wA, int wB, vector<int> &A, vector<int> &B){
    int cnt=0;
    if(n == 0){
        if(wA > wB){
            //cout << "aaa"<< wA <<" "<<wB << endl;
            return 1;
        }else{
            return 0;
        }
    }
    rep(i,N){
        if((flagA >> i) & 1) continue;
        int new_flagA = flagA | (1 << i);
        rep(j,N){
            if((flagB >> j) & 1) continue;
            int new_flagB = flagB | (1 << j);
            if(A[i] > B[j]){
                cnt += solve(new_flagA, new_flagB, n-1, wA+1, wB, A, B);
                
            }else if(A[i] < B[j]){
                cnt += solve(new_flagA, new_flagB, n-1, wA, wB+1, A, B);
            }else{
                cnt += solve(new_flagA, new_flagB, n-1, wA, wB, A, B);
            }
        }
    }
    return cnt;
}
int func(int n){
    if(n == 1){
        return 1;
    }else{
        return n*func(n-1);
    }
}

int main(){
    cin >> N;
    vector<int> A(N);
    vector<int> B(N);
    map<int,int> M;
    rep(i,N){
        cin >> A[i];
    }
    rep(i,N){
        cin >> B[i];
    }
    int nwin = solve(0, 0, N, 0, 0, A, B);

    cout<< double(nwin)/(func(N)*func(N)) <<endl;
}