#include <cstdio>
#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>
using namespace std;

// build prime table
class PrimeTable {
public:
    PrimeTable() {
        vector<bool> isPrime(maxn, true);
        isPrime[0] = isPrime[1] = false;
        for (int i = 2; i < maxn; i++) {
            if (!isPrime[i]) continue;
            for (int j = i + i; j < maxn; j += i) {
                isPrime[j] = false;
            }
        }
        for (int i = 0; i < isPrime.size(); i++) {
            if (isPrime[i]) prime.push_back(i);
        }
    }

    int findLargePrime(int n) {
         return *(lower_bound(prime.begin(), prime.end(), n));
    }

private:
    const int maxn = 100004;
    vector<int> prime;
};

class HashTable {
public:
    HashTable(int key) {
        this->key = key;
        this->table.resize(key, -1);
    }

    // quadrtic probing
    // h = ((val % key) + di) % key
    // key: table size
    // di:0*0, 1*1, 2*2, 3*3, ..., i*i; i <= table size
    bool insert(int val) {
        for (int i = 0; i < this->table.size(); i++) {
            int h = (val % this->key + i * i) % this->key;
            if (this->table[h] == -1) {
                this->table[h] = val;
                return true;
            }
        }
        return false;
    }

    // similar method with insert
    int searchCount(int val) {
        int cnt = 0;
        for (int i = 0; i < this->table.size(); i++) {
            cnt++;
            int h = (val % this->key + i * i) % this->key;
            if (this->table[h] == -1 || this->table[h] == val) {
                return cnt;
            }
        }
        cnt += 1;
        return cnt;
    }

private:
    vector<int> table;
    int key;
};

int main() {
    int mSize, n, m, e;
    cin >> mSize >> n >> m;
    PrimeTable pt;
    mSize = pt.findLargePrime(mSize);
    HashTable ht(mSize);
    for (int i = 0; i < n; i++) {
        cin >> e;
        if (!ht.insert(e)) cout << e << " cannot be inserted." << endl;
    }
    int searchCnt = 0;
    for (int i = 0; i < m; i++) {
        cin >> e;
        searchCnt += ht.searchCount(e);
    }
    cout << setiosflags(ios::fixed) << setprecision(1) << searchCnt / (double)m << endl;
    return 0;
}