N, M = (int(x) for x in input().split())

d={}
for i in range(1, N+1):
    d[i] = []

for i in range(M):
    U, V = (int(x) for x in input().split())
    d[U].append(V)
    d[V].append(U)

K=int(input())
if K >= 1:
    A=list(map(int, input().split()))
    A=set(A)
else:
    A = set()

visited=[[-1]*N for _ in range(5)]
visited[0][0] = 0
stack = [[1, 0]]
next_move = []
while stack:
    for i, j in stack:
        for k in d[i]:
            if k not in A:
                if visited[0][k-1] == -1:
                    visited[0][k-1] = visited[j][i-1] + 1
                    next_move.append([k, 0])
            else:
                if j == 4:
                    continue
                elif visited[j+1][k-1] == -1:
                    visited[j+1][k-1] = visited[j][i-1] + 1
                    next_move.append([k, j+1])
    
    stack, next_move = next_move, []

INF=float("inf")
ans = INF
for i in range(5):
    if visited[i][-1] != -1:
        ans = min(ans, visited[i][-1])

if ans != INF:
    print(ans)
else:
    print(-1)