n = int(input())
data = [set()]+[set(int(x) for x in input().split()) for _ in range(n)]

print(data)

def infl(num,data,visited):
    visited.add(num)
    res = data[num].copy()
    for x in data[num]:
        if x not in visited:
            res |= infl(x,data,visited)
    data[num] = res
    return data[num]

for x in range(len(data)):
    infl(x,data,set())

print([x for x in range(n) if len(data[x])>n])