N,X = map(int,input().split())
S = list(map(int,input().split()))

assert(2<=N<=2*10**5)
assert(0<=X<=10**9)
for i in range(N):
    assert(1<=S[i]<=10**9)

pre_A = [X-S[i] for i in range(N)]

wrong_A = sum(pre_A)

assert(-10**18<=wrong_A<=10**18)

print(X-wrong_A)