#include <bits/stdc++.h>
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define drep(i,j,n) for(int i=0;i<(int)(n-1);i++)for(int j=i+1;j<(int)(n);j++)
#define trep(i,j,k,n) for(int i=0;i<(int)(n-2);i++)for(int j=i+1;j<(int)(n-1);j++)for(int k=j+1;k<(int)(n);k++)
#define codefor int test;scanf("%d",&test);while(test--)
#define INT(...) int __VA_ARGS__;in(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;in(__VA_ARGS__)
#define yes(ans) if(ans)printf("yes\n");else printf("no\n")
#define Yes(ans) if(ans)printf("Yes\n");else printf("No\n")
#define YES(ans) if(ans)printf("YES\n");else printf("NO\n")
#define popcount(v) __builtin_popcount(v)
#define vector2d(type,name,h,...) vector<vector<type>>name(h,vector<type>(__VA_ARGS__))
#define vector3d(type,name,h,w,...) vector<vector<vector<type>>>name(h,vector<vector<type>>(w,vector<type>(__VA_ARGS__)))
#define umap unordered_map
#define uset unordered_set
using namespace std;
using ll = long long;
const int MOD=1000000007;
const int MOD2=998244353;
const int INF=1<<30;
const ll INF2=1LL<<60;
//入力系
void scan(int& a){scanf("%d",&a);}
void scan(long long& a){scanf("%lld",&a);}
template<class T,class L>void scan(pair<T, L>& p){scan(p.first);scan(p.second);}
template<class T,class U,class V>void scan(tuple<T,U,V>& p){scan(get<0>(p));scan(get<1>(p));scan(get<2>(p));}
template<class T> void scan(T& a){cin>>a;}
template<class T> void scan(vector<T>& vec){for(auto&& it:vec)scan(it);}
void in(){}
template <class Head, class... Tail> void in(Head& head, Tail&... tail){scan(head);in(tail...);}
//出力系
void print(const int& a){printf("%d",a);}
void print(const long long& a){printf("%lld",a);}
void print(const double& a){printf("%.15lf",a);}
template<class T,class L>void print(const pair<T, L>& p){print(p.first);putchar(' ');print(p.second);}
template<class T> void print(const T& a){cout<<a;}
template<class T> void print(const vector<T>& vec){if(vec.empty())return;print(vec[0]);for(auto it=vec.begin();++it!= vec.end();){putchar(' ');print(*it);}}
void out(){putchar('\n');}
template<class T> void out(const T& t){print(t);putchar('\n');}
template <class Head, class... Tail> void out(const Head& head,const Tail&... tail){print(head);putchar(' ');out(tail...);}
//デバッグ系
template<class T> void dprint(const T& a){cerr<<a;}
template<class T> void dprint(const vector<T>& vec){if(vec.empty())return;cerr<<vec[0];for(auto it=vec.begin();++it!= vec.end();){cerr<<" "<<*it;}}
void debug(){cerr<<endl;}
template<class T> void debug(const T& t){dprint(t);cerr<<endl;}
template <class Head, class... Tail> void debug(const Head& head, const Tail&... tail){dprint(head);cerr<<" ";debug(tail...);}
ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; }
ll modpow(ll a, ll b, ll p){ ll ans = 1; while(b){ if(b & 1) (ans *= a) %= p; (a *= a) %= p; b /= 2; } return ans; }
ll modinv(ll a, ll m) {ll b = m, u = 1, v = 0;while (b) {ll t = a / b;a -= t * b; swap(a, b);u -= t * v; swap(u, v);}u %= m;if (u < 0) u += m;return u;}
ll updivide(ll a,ll b){if(a%b==0) return a/b;else return (a/b)+1;}
template<class T> void chmax(T &a,const T b){if(b>a)a=b;}
template<class T> void chmin(T &a,const T b){if(b<a)a=b;}

/*string dijkstra(int sy,int sx,int gy,int gx){

}*/

int main(){
    int test=1000,sy,sx,gy,gx;
    int score;
    double d2;
    while(test--){
        cin>>sy>>sx>>gy>>gx;
        string s,t;
        if(gy>sy)s.resize(gy-sy,'D');
        else s.resize(sy-gy,'U');
        if(gx>sx)t.resize(gx-sx,'R');
        else t.resize(sx-gx,'L');
        cout<<s<<t<<endl;
        cin>>score;
    }
}
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#pragma GCC optimize("unroll-loops")
#include<bits/stdc++.h>
using namespace std;
//#include<atcoder/all>
//using namespace atcoder;
using ll = long long;
#define For(i,n,k) for(int i=(n);i<(k);i++)
#define ALL(a) (a).begin(),(a).end()
const int MAX_N = 18;
vector<vector<int>> exdist(MAX_N, vector<int> (MAX_N, 1e9));
int k;
vector<int> c(MAX_N);
int dp[1<<MAX_N][MAX_N];
int dfs(int s, int v){
    if(dp[s][v] >= 0){
        return dp[s][v];
    }

    if(s == (1<<k)-1){
        return dp[s][v] = 0;
    }

    int ans = 1e9+100;
    For(u,0,k){
        if(!(s >> u & 1)){
            ans = min(ans, dfs(s | 1 << u, u) + exdist[v][u]);
        }
    }

    dp[s][v] = ans;
    return ans;
}
void Main(){
    int n, m;
    cin >> n >> m;
    vector<vector<int>> graph(n+1);
    For(i,0,m){
        int a, b;
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    cin >> k;
    For(i,0,k){
        cin >> c[i];
    }
    For(i,0,k){
        int cnt = 0;
        vector<int> dist(n+1, 1e9);
        queue<int> q;
        dist[c[i]] = 0;
        q.push(c[i]);
        while(!q.empty()){
            auto now = q.front();
            q.pop();
            for(auto to:graph[now]){
                if(dist[to] > dist[now] + 1){
                    dist[to] = dist[now] + 1;
                    q.push(to);
                }
            }
        }
        For(j,0,k) exdist[i][j] = dist[c[j]];
    }
    For(i,0,k+1){
        exdist[i][k] = 0;
        exdist[k][i] = 0;
    }
    memset(dp,-1,sizeof(dp));
    int ans = dfs(0,k) + 1;
    cout << (ans >= 1e9 ? -1 : ans) << endl;
}
int main(){
    Main();
    /*
    東方風神録は神が出てくるので当然神ゲー
    */
    return 0;
}