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

const int MAXN = 1000002;
const int INF = 1000000000;

int D[MAXN];
int a[MAXN];
vector < int > G[MAXN];
int n,m,tm,u,i,k,v,v1,v2,nt,wait;



class Mycmp
{
public:
    bool operator () ( int v1, int v2)
    {
        if (D[v1] < D[v2])
            return true;
        if (D[v2] < D[v1])
            return false;
        if (D[v1] == D[v2])
            return v1>v2;
    }
};
set <int,Mycmp > X;


int main()
{
    freopen("badsanta.in","r",stdin);
    freopen("badsanta.out","w",stdout);
    cin >> n >> m >>k;
    for (i=0; i<m; i++)
    {
        cin >> v1 >> v2;
        G[v1].push_back(v2);
        G[v2].push_back(v1);
    }
    for (i=0; i<k; i++)
        cin >> a[i];
    if (a[0] == 1)
    {
        cout<< -1<<endl;
        return 0;
    }


    for (i=1; i<=n; i++)
        D[i] = INF;
    D[1] = 0;
    X.insert(1);
    while (X.size() >0)
    {
        v = *X.begin();
        X.erase(X.begin());
        if (D[v] == INF)
            break;

        for (i=0; i < G[v].size(); i++)
        {
            u = G[v][i];
            tm = D[v];
            /*if (make_pair(a [tm%k]  ,  a[(tm+1) % k]) == make_pair(u,v))
                continue;*/

            for (wait = 0; wait <= 20; wait ++)
            {
                nt = tm + wait;
                if (a[nt %k ] == v)
                    break;
                if (a[(tm+wait+1)%k] == v && u == a[(tm+wait) % k])
                    continue;
                if (u == a[(tm+wait+1) %k])
                    continue;
                if (D[u] > tm +wait +1)
                {
                    X.erase(u);
                    D[u] = tm + wait + 1;
                    X.insert(u);
                    //break;
                }
            }
        }
    }
    if (D[n] == INF)
        cout << -1 <<endl;
    else
        cout <<D[n] <<endl;
    return 0;
}