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):
        x,y = [int(i) for i in stdin.readline().split()]
        oda[x].append(y)
        vissza[y].append(x)

    sor = [K]
    vvolt = [False] * (N+1)
    vvolt[K] = True
    while sor != []:
        P = sor.pop(0)
        for v in vissza[P]:
            if not vvolt[v]:
                vvolt[v] = True
                sor.append(v)       
    S = set()
    for o in oda[K]:
        S.add(o)
        
    sor = [K]
    volt = [False] * (N+1)
    volt[K] = True
    while sor != []:
        P = sor.pop(0)
        for o in oda[P]:
            if not volt[o]:
                volt[o] = True
                sor.append(o)
                if vvolt[o]:
                    for od in oda[o]:
                        S.add(od)
    S.remove(K)
    print(len(S))
    print(*S)
    
main()