N, X = map(int, input().split())
assert 2 <= N <= 2 * 10 ** 5
assert 0 <= X <= 10 ** 9

S = [int(a) for a in input().split()]
assert len(S) == N
for s in S:
    assert 1 <= s <= 10 ** 9

ans = sum(S) - X * (N - 1)
assert ans != 0

for i, s in enumerate(S):
    if s == ans * 2:
        S[i] -= ans
        break
else:
    assert False

print(ans)