'''
N,M,K = map(int,input().split())
el = []
for i in range(M):
    tol,ig = map(int,input().split())
    el.append([tol,ig,0,0])
'''
be = open("be2.txt")
N,M,K = map(int,be.readline().split())
el = []
fel = []
for i in range(N+1):
    el.append([])
    fel.append([])
for i in range(M):
    tol,ig = map(int,be.readline().split())
    el[tol].append(ig)
    fel[ig].append(tol)
be.close()
sor = [K]
szin = [0] * (N+1)
szin[K] = 1
while len(sor)>0:
    AktCsucs = sor[-1]
    szin[AktCsucs] = 2
    sor.pop()
    for j in fel[AktCsucs]:
        if szin[j] == 0:
            sor.append(j)
            szin[j] = 1
halmaz = set()
for i in range(1,N+1):
    if szin[i] != 0:
        if i != K:
            halmaz.add(i)
        for x in el[i]:
            if x != K:
                halmaz.add(x)
print(len(halmaz))
for x in halmaz:
    print(x,end=" ")