Buggy python submission (verdict: Time Limit Exceeded):
import bisect
N, = map(int, input().split())
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
def g(x):
    mx, mn = N, -1
    idx = mx//2
    while mx-mn>1:
        if Q[idx] >= x:
            mx, idx = idx, (idx+mn)//2
            continue
        mn, idx = idx, (idx+mx)//2
    return idx+1
mxk = 29
msk = (1<<mxk) - 1
msk2 = (1<<(mxk-1))
r = 0
for i in range(mxk):
    for j in range(N):
        Q[j] = Q[j] & msk
        P[j] = P[j] & msk
    msk >>= 1
    Q.sort()
    b = 0
    for p in P:
        x = bisect.bisect_left(Q, 2*msk2 - (p&msk))
        z = bisect.bisect_left(Q, msk2 - (p&msk),0,x)
        if p & msk2:
            b += z+N-x
        else:
            b += x-z
    if b%2:
        r += 1<<(mxk-1-i)
    msk2 >>= 1
print(r)


Fixed submission:
N, = map(int, input().split())
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
mxk = 29
msk = (1<<mxk) - 1
msk2 = (1<<(mxk-1))
r = 0
for i in range(mxk):
    # 下からiビット目をみる
    for j in range(N):
        Q[j] = Q[j] & msk
        P[j] = P[j] & msk
    msk >>= 1
    P.sort()
    Q.sort()
    j1 = N-1
    j2 = N-1
    b = 0
    ss = N
#    print(P, Q)
    for l in range(N):
        if P[l] & msk2:
            ss = l
            break
        k1 = msk2 - (P[l]&msk)
        k2 = k1 + msk2
        while j1 >= 0:
            if Q[j1] < k1:
                break
            j1 -= 1
        while j2 >= 0:
            if Q[j2] < k2:
                break
            j2 -= 1
        b += j2 - j1
#        print("a",j2-j1,k1,k2,j1,j2)

    j1 = N-1
    j2 = N-1
#    print(ss)
    for l in range(ss, N):
        k1 = msk2 - (P[l]&msk)
        k2 = k1 + msk2
        while j1 >= 0:
            if Q[j1] < k1:
                break
            j1 -= 1
        while j2 >= 0:
            if Q[j2] < k2:
                break
            j2 -= 1
#        print("b",j1 - j2 + N)
        b += j1 + N - j2

#    b = 0
#    for p in P:
#        if p & msk2:
#            x = g(2*msk2 - (p&msk))
#            z = g(msk2 - (p&msk))
#            b += z+N-x
#        else:
#            x = g(2*msk2 - (p&msk))
#            z = g(msk2 - (p&msk))
#            b += x-z
#    print(b, r, i)
    if b%2:
        r += 1<<(mxk-1-i)
    msk2 >>= 1
print(r)

Buggy python submission (verdict: Time Limit Exceeded):
import bisect
N, = map(int, input().split())
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
def g(x):
    mx, mn = N, -1
    idx = mx//2
    while mx-mn>1:
        if Q[idx] >= x:
            mx, idx = idx, (idx+mn)//2
            continue
        mn, idx = idx, (idx+mx)//2
    return idx+1
mxk = 29
msk = (1<<mxk) - 1
msk2 = (1<<(mxk-1))
r = 0
for i in range(mxk):
    for j in range(N):
        Q[j] = Q[j] & msk
        P[j] = P[j] & msk
    msk >>= 1
    Q.sort()
    b = 0
    for p in P:
        x = bisect.bisect_left(Q, 2*msk2 - (p&msk))
        z = bisect.bisect_left(Q, msk2 - (p&msk))
        if p & msk2:
            b += z+N-x
        else:
            b += x-z
    if b%2:
        r += 1<<(mxk-1-i)
    msk2 >>= 1
print(r)


Fixed submission:
N, = map(int, input().split())
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
mxk = 29
msk = (1<<mxk) - 1
msk2 = (1<<(mxk-1))
r = 0
for i in range(mxk):
    # 下からiビット目をみる
    for j in range(N):
        Q[j] = Q[j] & msk
        P[j] = P[j] & msk
    msk >>= 1
    P.sort()
    Q.sort()
    j1 = N-1
    j2 = N-1
    b = 0
    ss = N
#    print(P, Q)
    for l in range(N):
        if P[l] & msk2:
            ss = l
            break
        k1 = msk2 - (P[l]&msk)
        k2 = k1 + msk2
        while j1 >= 0:
            if Q[j1] < k1:
                break
            j1 -= 1
        while j2 >= 0:
            if Q[j2] < k2:
                break
            j2 -= 1
        b += j2 - j1
#        print("a",j2-j1,k1,k2,j1,j2)

    j1 = N-1
    j2 = N-1
#    print(ss)
    for l in range(ss, N):
        k1 = msk2 - (P[l]&msk)
        k2 = k1 + msk2
        while j1 >= 0:
            if Q[j1] < k1:
                break
            j1 -= 1
        while j2 >= 0:
            if Q[j2] < k2:
                break
            j2 -= 1
#        print("b",j1 - j2 + N)
        b += j1 + N - j2

#    b = 0
#    for p in P:
#        if p & msk2:
#            x = g(2*msk2 - (p&msk))
#            z = g(msk2 - (p&msk))
#            b += z+N-x
#        else:
#            x = g(2*msk2 - (p&msk))
#            z = g(msk2 - (p&msk))
#            b += x-z
#    print(b, r, i)
    if b%2:
        r += 1<<(mxk-1-i)
    msk2 >>= 1
print(r)

Buggy python submission (verdict: Time Limit Exceeded):
N, = map(int, input().split())
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
def g(x):
    mx, mn = N, -1
    idx = mx//2
    while mx-mn>1:
        if Q[idx] >= x:
            mx, idx = idx, (idx+mn)//2
            continue
        mn, idx = idx, (idx+mx)//2
    return idx+1
    
def f(x):
    # q < x の数を探す
    c = 0
    for i, q in enumerate(Q):
        if q < x:
            c+=1
    return c
mxk = 29
msk = (1<<mxk) - 1
msk2 = (1<<(mxk-1))
r = 0
for i in range(mxk):
    # 下からiビット目をみる
    for j in range(N):
        Q[j] = Q[j] & msk
        P[j] = P[j] & msk
    msk >>= 1
    Q.sort()
#    print(mxk-1-i, P)
#    print(Q)
    b = 0
    for p in P:
        if p & msk2:
            # i bit が1になる
            # q < msk2 - p&msk
            # msk2 <= q < 2*msk2 - p
            # 0
            # msk2-p&msk <= q < msk2 
            # 2*msk2 - p <= q
            x = g(2*msk2 - (p&msk))
            z = g(msk2 - (p&msk))
#            print(x, y, z, msk2)
            b += z+N-x
#            print(p, z+N-x, msk2)
        else:
            x = g(2*msk2 - (p&msk))
            z = g(msk2 - (p&msk))
#            print(p, x, y, z)
#            print(2*msk2 - p&msk, msk2, msk2 - p&msk)
            b += x-z
#            print(p, x-z)
#    print(b)
    if b%2:
        r += 1<<(mxk-1-i)
    msk2 >>= 1
print(r)


Fixed submission:
N, = map(int, input().split())
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
mxk = 29
msk = (1<<mxk) - 1
msk2 = (1<<(mxk-1))
r = 0
for i in range(mxk):
    # 下からiビット目をみる
    for j in range(N):
        Q[j] = Q[j] & msk
        P[j] = P[j] & msk
    msk >>= 1
    P.sort()
    Q.sort()
    j1 = N-1
    j2 = N-1
    b = 0
    ss = N
#    print(P, Q)
    for l in range(N):
        if P[l] & msk2:
            ss = l
            break
        k1 = msk2 - (P[l]&msk)
        k2 = k1 + msk2
        while j1 >= 0:
            if Q[j1] < k1:
                break
            j1 -= 1
        while j2 >= 0:
            if Q[j2] < k2:
                break
            j2 -= 1
        b += j2 - j1
#        print("a",j2-j1,k1,k2,j1,j2)

    j1 = N-1
    j2 = N-1
#    print(ss)
    for l in range(ss, N):
        k1 = msk2 - (P[l]&msk)
        k2 = k1 + msk2
        while j1 >= 0:
            if Q[j1] < k1:
                break
            j1 -= 1
        while j2 >= 0:
            if Q[j2] < k2:
                break
            j2 -= 1
#        print("b",j1 - j2 + N)
        b += j1 + N - j2

#    b = 0
#    for p in P:
#        if p & msk2:
#            x = g(2*msk2 - (p&msk))
#            z = g(msk2 - (p&msk))
#            b += z+N-x
#        else:
#            x = g(2*msk2 - (p&msk))
#            z = g(msk2 - (p&msk))
#            b += x-z
#    print(b, r, i)
    if b%2:
        r += 1<<(mxk-1-i)
    msk2 >>= 1
print(r)

Buggy python submission (verdict: Time Limit Exceeded):
N, = map(int, input().split())
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
def f(x):
    # q < x の数を探す
    c = 0
    for i, q in enumerate(Q):
        if q < x:
            c+=1
    return c
mxk = 28
msk = (1<<mxk) - 1
msk2 = (1<<(mxk-1))
r = 0
for i in range(mxk):
    # 下からiビット目をみる
    for j in range(N):
        Q[j] = Q[j] & msk
        P[j] = P[j] & msk
    msk >>= 1
    Q.sort()
#    print(mxk-1-i, P)
#    print(Q)
    b = 0
    for p in P:
        if p & msk2:
            # i bit が1になる
            # q < msk2 - p&msk
            # msk2 <= q < 2*msk2 - p
            # 0
            # msk2-p&msk <= q < msk2 
            # 2*msk2 - p <= q
            x = f(2*msk2 - (p&msk))
            z = f(msk2 - (p&msk))
#            print(x, y, z, msk2)
            b += z+N-x
#            print(p, z+N-x, msk2)
        else:
            x = f(2*msk2 - (p&msk))
            z = f(msk2 - (p&msk))
#            print(p, x, y, z)
#            print(2*msk2 - p&msk, msk2, msk2 - p&msk)
            b += x-z
#            print(p, x-z)
#    print(b)
    if b%2:
        r += 1<<(mxk-1-i)
    msk2 >>= 1
print(r)


Fixed submission:
N, = map(int, input().split())
P = list(map(int, input().split()))
Q = list(map(int, input().split()))
mxk = 29
msk = (1<<mxk) - 1
msk2 = (1<<(mxk-1))
r = 0
for i in range(mxk):
    # 下からiビット目をみる
    for j in range(N):
        Q[j] = Q[j] & msk
        P[j] = P[j] & msk
    msk >>= 1
    P.sort()
    Q.sort()
    j1 = N-1
    j2 = N-1
    b = 0
    ss = N
#    print(P, Q)
    for l in range(N):
        if P[l] & msk2:
            ss = l
            break
        k1 = msk2 - (P[l]&msk)
        k2 = k1 + msk2
        while j1 >= 0:
            if Q[j1] < k1:
                break
            j1 -= 1
        while j2 >= 0:
            if Q[j2] < k2:
                break
            j2 -= 1
        b += j2 - j1
#        print("a",j2-j1,k1,k2,j1,j2)

    j1 = N-1
    j2 = N-1
#    print(ss)
    for l in range(ss, N):
        k1 = msk2 - (P[l]&msk)
        k2 = k1 + msk2
        while j1 >= 0:
            if Q[j1] < k1:
                break
            j1 -= 1
        while j2 >= 0:
            if Q[j2] < k2:
                break
            j2 -= 1
#        print("b",j1 - j2 + N)
        b += j1 + N - j2

#    b = 0
#    for p in P:
#        if p & msk2:
#            x = g(2*msk2 - (p&msk))
#            z = g(msk2 - (p&msk))
#            b += z+N-x
#        else:
#            x = g(2*msk2 - (p&msk))
#            z = g(msk2 - (p&msk))
#            b += x-z
#    print(b, r, i)
    if b%2:
        r += 1<<(mxk-1-i)
    msk2 >>= 1
print(r)