from sys import stdin,stdout

def main():
    N,M,K = [int(i) for i in input().split()]
    oda = [[] for i in range(N+1)]
    vissza = [[] for i in range(N+1)]
    for i in range(M):
        k,v = [int(i) for i in stdin.readline().split()]
        oda[k].append(v)
        vissza[v].append(k)

    def BSF(S,gr):
        sor = [S]
        volt = [S]
        while sor != []:
            P = sor.pop(0)
            for x in gr[P]:
                if x not in volt:
                    volt.append(x)
                    sor.append(x)
        return volt

    A = BSF(K,oda)
    B = BSF(K,vissza)
    tura = oda[K]
    db = len(tura)
    for x in B:
        for y in oda[x]:
            if y != K and y not in tura:
                tura.append(y)
                db += 1

    print(db)
    print(*tura)

main()