#!/usr/bin/env python


def read_input():
    with open('input.txt', 'r') as f:
        data  = f.read().splitlines()
        return [ int(x) for x in data[0].split(" ")]


def get_node_meta(data, pos):
    num_ch = data[pos]
    num_m = data[pos+1]
    len_ch = 0	# total length of children
    values = [0] * num_ch
    value = 0

    for ch in range(num_ch):
        (ch_len, ch_value) = get_node_meta(data, pos+2+len_ch)
        len_ch += ch_len
        values[ch] = ch_value

    meta = data[pos+2+len_ch:pos+2+len_ch+num_m]

    # do not have children
    if num_ch == 0:
        value = sum(meta)
    else:
        for m in meta:
            if m <= num_ch:
                value += values[m-1]
    return (len_ch+2+num_m, value)

tree = read_input()
(_, value) = get_node_meta(tree, 0)
print(value)