count = int(input())
i = 0

courses = []

while True:
    if i >= count:
        break
    user = input()
    courses.append(user)
    i += 1

all_courses = []
for course in courses:
    all_courses.extend(course.split(" "))

all_courses = set(all_courses)

container = []
for course in all_courses:
    temp_result = []
    for e, student_course in enumerate(courses):
        if course in student_course:
            temp_result.append(True)
        else:
            temp_result.append(False)
            break
    if False not in temp_result:
        container.append(course)

container = sorted(container)
result = "\n".join(container)
print(result)