from sys import stdin, stdout
def main():
    n,m,l = map(int,stdin.readline().split())
    nodes:list[set[int]]=[]

    for i in range(n):
        nodes.append(set([i]))

    for i in range(m):
        a,b = map(int,stdin.readline().split())
        nodes[a].add(b)
        nodes[b].add(a)


    #print(nodes)
    patrols=stdin.readline().split()
    patrols = [int(i) for i in patrols]
    cop_loc:int=patrols[0]
    minutes:int=0
    first_it_list:set[int]=[0]
    #BREADTH FIRST SEARCH
    def do_layer(first_it_l:set[int]) ->set[int]:
        rt_set:set[int]=set([])
        for i in first_it_l:
            for j in nodes[i]:
                if j!=cop_loc:
                    rt_set.add(j)
        return rt_set
    while not first_it_list.__contains__(n-1):
        minutes+=1
        cop_loc=patrols[minutes%len(patrols)]
        first_it_list=do_layer(first_it_list)
    stdout.write(str(minutes))

main()