def main():
    import sys
    input = sys.stdin.read().split()
    ptr = 0
    N = int(input[ptr])
    ptr += 1
    M = int(input[ptr])
    ptr += 1

    min_post = float('inf')
    max_post = -float('inf')
    min_all = float('inf')
    max_all = -float('inf')

    for _ in range(M):
        x_i = int(input[ptr])
        ptr += 1
        d_i = int(input[ptr])
        ptr += 1
        min_post = min(min_post, x_i)
        max_post = max(max_post, x_i)
        min_all = min(min_all, x_i)
        max_all = max(max_all, x_i)
        for __ in range(d_i):
            y_j = int(input[ptr])
            ptr += 1
            min_all = min(min_all, y_j)
            max_all = max(max_all, y_j)
    
    post_span = max_post - min_post
    total_span = max_all - min_all
    print(total_span + post_span)

if __name__ == "__main__":
    main()