#include<iostream>
#include<algorithm>
#include<cstring>

using namespace std;

const int N = 10010;

int s,n,m;
int h[N];

bool is_prime(int x)
{
    if(x==1) return 0;
    for(int i = 2; i*i<=x; i++)
        if(x%i==0) return 0;
    return 1;
}

int find(int x,int &cnt)
{
    int t  = x % s;
    cnt = 1;

    for(int k = 0; k<s; k++,cnt++)
    {
        int i = (t+k*k)%s;
        if(!h[i] || h[i]==x) return i;
    }
    return -1;
}

int main()
{
    cin>>s>>n>>m;
    while(!is_prime(s)) s++;

    for(int i = 0; i<n; i++)
    {
        int x,count;
        cin>>x;
        int t = find(x,count);
        if(t==-1) printf("%d cannot be inserted.\n",x);
        else h[t] = x;
    }

    int cnt = 0;
    for(int i = 0; i<m; i++)
    {
        int x,count;
        cin>>x;
        find(x,count);
        cnt += count;
    }
    printf("%.1lf\n",(double)cnt/m);
    return 0;
}