H.py

def main():
    n = int(input())

    product_min = {}
    product_current = {}

    for _ in range(n):
        visit = input().split()
        num_of_products = visit[0]
        products = visit[1:]

        for p in product_current:
            if p in products:
                product_min[p] = min(
                    product_min.get(p, product_current[p]), product_current[p]
                )
            else:
                product_current[p] += 1

        for p in products:
            if p not in product_current:
                product_current[p] = 0

    print(len(product_min))
    for p, v in sorted(product_min.items()):
        print(p, v + 1)


if __name__ == "__main__":
    main()