from functools import cache

@cache
def f(p):
    ans = -sum(p)
    if not p:
        return 0
    n = len(p)
    for i in range(n):
        x = p[i]
        if x <= k:
            ans = max(ans, x - f(tuple(sorted(p[:i] + p[i+1:]))))
        else:
            for s in range(1, x):
                ans = max(ans, -f(tuple(sorted(p[:i] + p[i+1:] + (s, x - s)))))
    return ans

from random import *
# k = int(input())
# k=3

def solve(k, inp):
    d1 = []
    d2 = []
    for x in inp:
        if x <= k:
            d1.append(x)
        else:
            d2.append(x)
    d1.sort(reverse=True)
    res = sum(d1[0::2]) - sum(d1[1::2])
    turn = len(d1) % 2
    if sum(d2) % 2:
        if (turn + len(d2)) % 2 == 0:
            res += 1
        else:
            res -= 1
    return res

for _ in range(0):
    k = randrange(1, 6)
    inp = tuple(sorted(randrange(1, 10) for _ in range(randrange(1, 5))))
    f.cache_clear()
    res = solve(k, inp)
    # print(k, inp, f(inp), res)
    assert f(inp) == res
# print(f(inp))

n, k = map(int, input().split())
a = tuple(sorted(map(int, input().split())))
print((solve(k, a) + sum(a)) // 2)