#include <bits/stdc++.h>
using namespace std;

using edge = pair<int, int>;

int main()
{
    int n, m, k;
    cin >> n >> m >> k;
    vector<bool> must(m);
    for (int i = 0; i < k; i++)
    {
        int r;
        cin >> r;
        r--;
        must.at(r) = true;
    }
    const int s = 1 << k;
    /*
    vector<pair<int, short>> to[n * s];
    int idx = 0;
    for (int i = 0; i < m; i++)
    {
        int a, b, c;
        cin >> a >> b >> c;
        a--;
        b--;
        for (int j = 0; j < s; j++)
        {
            if (must.at(i))
            {
                to[a * s + j].emplace_back(b * s + (j | (1 << idx)), c);
                to[b * s + j].emplace_back(a * s + (j | (1 << idx)), c);
            }
            else
            {
                to[a * s + j].emplace_back(b * s + j, c);
                to[b * s + j].emplace_back(a * s + j, c);
            }
        }
        if (must.at(i))
        {
            idx++;
        }
    }
    */
    vector<int> dist(n * s, 2e9);
    /*
    priority_queue<edge, vector<edge>, greater<edge>> q;
    q.emplace(0, 0);
    while (not q.empty())
    {
        auto [d0, v] = q.top();
        q.pop();
        if (d0 >= dist.at(v))
        {
            continue;
        }
        dist.at(v) = d0;
        for (auto &&[c, d_edge] : to[v])
        {
            if (d0 + d_edge >= dist.at(c))
            {
                continue;
            }
            q.emplace(d0 + d_edge, c);
        }
    }
    */
    cout << dist.back() << endl;
    return 0;
}