import sys
import re

pat = re.compile('Valve ([A-Z]{2}) has flow rate=([0-9]+); tunnels? leads? to valves? ([ ,A-Z]+)')
P = dict()
for i,l in enumerate(sys.stdin.read().splitlines()):
    g = pat.search(l)
    p = int(g[2])
    P[g[1]] = (i, p, g[3].split(", "))
    
STEPS = int(sys.argv[1])
ALLO = 0
for _,(i,p,_) in P.items():
    if p == 0:
        ALLO = ALLO | (1<<i) 

cache = {}
def step(pos="AA", left=STEPS, opens=ALLO):
    """
    opens store valves openess 0: closed, 1: open
                         1 2 3 4 5 6 7 8 9 10
    eg: 0b1000011110 ->  0 1 1 1 1 0 0 0 0 1

    return : score = max(p*left + open valve if not open and continue, not open valve and continue)
    """
    if left <= 0:
        return 0
    key = (pos, left, opens)
    r = cache.get(key, -1)
    if r >= 0:
        return r
    (i, p, nh) = P[pos]
    is_open = opens & (1 << i)
    #print(minutes, path, i, bool(is_open), p, nh)
    a = 0
    if not is_open:  # also means 0 - worth opening valve ?
        #print("open", i)
        left -= 1 # cost to open
        opens = opens | (1<<i)
        a = p*(left+30-STEPS) + max(step(n, left-1, opens) for n in nh)
    b = max(step(n, left-1, opens) for n in nh)
    r = max(a,b)
    cache[key] = r
    return r

print(step())