Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline
n, m = map(int, input().split())
x = list(map(int, input().split()))
a = 0
b = 0
ans = 0
mae = 0
b = [0] * 40
for i in range(40):
    for k in x:
        b[i] += (k & (1 << i)) >> i

c = [0] * 40
if b[0] > n - b[0]:
    c[0] = b[0]
else:
    c[0] = n - b[0]
for i in range(1,40):
    ansb = 0
    if b[i] > n - b[i]:
        ansb += b[k] << k
    else:
        ansb += n - b[k] << k
    c[i] = c[i-1] + ansb
for i in range(39, -1, -1):
    if m & (1 << i):
        ansb = mae
        ansb += b[i] << i
        ansb += c[i]
        if ans < ansb:
            ans = ansb
        mae += n-b[i] << i
    else:
        mae += b[i] << i
ans = max(ans, mae)
print(ans)


Fixed submission:
#A

#B
"""
n = int(input())
l = list(map(int, input().split()))
l.sort()
ans = sum(l) - 2*l[-1]
if ans > 0:
    print("Yes")
else:
    print("No")
"""

#C
"""
import bisect
n, m = map(int, input().split())
x = list(map(int, input().split()))
x.sort()
xb = [abs(x[i] - x[i + 1]) for i in range(m-1)]
xb.sort(reverse=True)
ans = sum(xb[n - 1::])
print(ans)
"""

#D
n, m = map(int, input().split())
x = list(map(int, input().split()))
a = 0
b = 0
ans = 0
ansb = 0
mae = 0
b = [0 for i in range(40)]
for i in range(40):
    for k in x:
        b[i] += (k & (1 << i)) >> i

for i in range(39, -1, -1):
    if m & (1 << i) > 0:
        ansb = mae
        ansb += b[i] << i
        for k in range(i):
            ansb += max(b[k], n-b[k]) << k
        ans = max(ans, ansb)
        mae += (n-b[i]) << i
    else:
        mae += b[i] << i
ans = max(ans, mae)
print(ans)

Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline
n, m = map(int, input().split())
x = list(map(int, input().split()))
a = 0
b = 0
ans = 0
mae = 0
b = [0] * 40
for i in range(40):
    for k in x:
        b[i] += (k & (1 << i)) >> i

c = [0] * 40
if b[0] > n - b[0]:
    c[0] = b[0]
else:
    c[0] = n - b[0]
for i in range(1,40):
    ansb = 0
    if b[i] > n - b[i]:
        ansb += b[k] << k
    else:
        ansb += n - b[k] << k
    c[i] = c[i-1] + ansb
for i in range(39, -1, -1):
    if m & (1 << i):
        ansb = mae
        ansb += b[i] << i
        ansb += c[k]
        if ans < ansb:
            ans = ansb
        mae += n-b[i] << i
    else:
        mae += b[i] << i
ans = max(ans, mae)
print(ans)


Fixed submission:
#A

#B
"""
n = int(input())
l = list(map(int, input().split()))
l.sort()
ans = sum(l) - 2*l[-1]
if ans > 0:
    print("Yes")
else:
    print("No")
"""

#C
"""
import bisect
n, m = map(int, input().split())
x = list(map(int, input().split()))
x.sort()
xb = [abs(x[i] - x[i + 1]) for i in range(m-1)]
xb.sort(reverse=True)
ans = sum(xb[n - 1::])
print(ans)
"""

#D
n, m = map(int, input().split())
x = list(map(int, input().split()))
a = 0
b = 0
ans = 0
ansb = 0
mae = 0
b = [0 for i in range(40)]
for i in range(40):
    for k in x:
        b[i] += (k & (1 << i)) >> i

for i in range(39, -1, -1):
    if m & (1 << i) > 0:
        ansb = mae
        ansb += b[i] << i
        for k in range(i):
            ansb += max(b[k], n-b[k]) << k
        ans = max(ans, ansb)
        mae += (n-b[i]) << i
    else:
        mae += b[i] << i
ans = max(ans, mae)
print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
#A

#B
"""
n = int(input())
l = list(map(int, input().split()))
l.sort()
ans = sum(l) - 2*l[-1]
if ans > 0:
    print("Yes")
else:
    print("No")
"""

#C
"""
import bisect
n, m = map(int, input().split())
x = list(map(int, input().split()))
x.sort()
xb = [abs(x[i] - x[i + 1]) for i in range(m-1)]
xb.sort(reverse=True)
ans = sum(xb[n - 1::])
print(ans)
"""

#D
n, m = map(int, input().split())
x = list(map(int, input().split()))
a = []
c = []
xb = []
mb = m + 1
for k in x:
    b = []
    for i in range(39,-1,-1):
        if 2 ** i <= k:
            b.append(1)
            k -= 2 ** i
        else:
            b.append(0)
    xb.append(b)
for i in range(39,-1,-1):
    if 2 ** i <= m:
        a.append(1)
        m -= 2 ** i
    else:
        a.append(0)
m = mb
mb -= 1
for i in range(39,-1,-1):
    if 2 ** i <= m:
        c.append(1)
        m -= 2 ** i
    else:
        c.append(0)
ans = 0
for i in range(len(c)):
    ansd = 0
    ansc = []
    if c[i] == 1:  
        for k in range(i):
            ansb = 0
            for l in range(n):
                if c[k] != xb[l][k]:
                    ansb += 1
            ansc.append(ansb)
        k = i
        ansb = 0
        for l in range(n):
            if 0 != xb[l][k]:
                ansb += 1
        ansc.append(ansb)
        for k in range(i+1, len(c)):
            count0 = 0
            count1 = 0
            for l in range(n):
                if xb[l][k] == 0:
                    count0 += 1
                else:
                    count1 += 1
            ansc.append(max(count0, count1))
        ansc = list(reversed(ansc))
        for k in range(40):                
            ansd += ansc[k] * 2 ** k
        ans = max(ansd, ans)
print(ans)


        





Fixed submission:
#A

#B
"""
n = int(input())
l = list(map(int, input().split()))
l.sort()
ans = sum(l) - 2*l[-1]
if ans > 0:
    print("Yes")
else:
    print("No")
"""

#C
"""
import bisect
n, m = map(int, input().split())
x = list(map(int, input().split()))
x.sort()
xb = [abs(x[i] - x[i + 1]) for i in range(m-1)]
xb.sort(reverse=True)
ans = sum(xb[n - 1::])
print(ans)
"""

#D
n, m = map(int, input().split())
x = list(map(int, input().split()))
a = 0
b = 0
ans = 0
ansb = 0
mae = 0
b = [0 for i in range(40)]
for i in range(40):
    for k in x:
        b[i] += (k & (1 << i)) >> i

for i in range(39, -1, -1):
    if m & (1 << i) > 0:
        ansb = mae
        ansb += b[i] << i
        for k in range(i):
            ansb += max(b[k], n-b[k]) << k
        ans = max(ans, ansb)
        mae += (n-b[i]) << i
    else:
        mae += b[i] << i
ans = max(ans, mae)
print(ans)