N,M = map(int,input().split())
nodes = []
for i in range(M):
    a,b = map(int,input().split())
    nodes.append((a-1,b-1))
K = int(input())
if K > 0:
    A = list(map(int,input().split()))
else:
    A = []

iwaiset = set()
for i in A:
    iwaiset.add(i-1)

node = [[] for _ in range(5*N)]

for a,b in nodes:
    if b in iwaiset:
        node[a].append(b+N)
        node[a+N].append(b+N*2)
        node[a+N*2].append(b+N*3)
        node[a+N*3].append(b+N*4)
    else:
        node[a].append(b)
        node[a+N].append(b)
        node[a+N*2].append(b)
        node[a+N*3].append(b)
        node[a+N*4].append(b)
    if a in iwaiset:
        node[b].append(a+N)
        node[b+N].append(a+N*2)
        node[b+N*2].append(a+N*3)
        node[b+N*3].append(a+N*4)
    else:
        node[b].append(a)
        node[b+N].append(a)
        node[b+N*2].append(a)
        node[b+N*3].append(a)
        node[b+N*4].append(a)

dist = [10**18 for _ in range(5*N)]
dist[0] = 0

queue = [0]
while queue:
    v = queue.pop(0)
    for u in node[v]:
        if dist[u] == 10**18:
            dist[u] = dist[v] + 1
            queue.append(u)

print(min(dist[N-1],dist[2*N-1],dist[3*N-1],dist[4*N-1],dist[5*N-1]) if min(dist[N-1],dist[2*N-1],dist[3*N-1],dist[4*N-1],dist[5*N-1]) != 10**18 else -1)