#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
#define PI acos(-1.0)
#define INF 0x3f3f3f3f
#define P pair<int, int>
#define debug(x) cout << (#x) << ": " << (x) << " "
#define fastio ios::sync_with_stdio(false), cin.tie(0)
const int mod = 1e9 + 7;
const int M = 6000000 + 10;
const int N = 20 + 10;

int n, e, a[N][N];
int tree[M][2], cnt;
vector<int> v11[N], vnn[N];

void add(int x)
{
    int now = 1;
    for(int i = 31; i >= 0; -- i) {
        int &son = tree[now][(x >> i) & 1];
        if(!son) son = ++cnt;
        now = son;
    }
}

int query(int x)
{
    int now = 1, ans = 0;
    for(int i = 31; i >= 0; -- i) {
        int &son = tree[now][!((x >> i) & 1)];
        if(son) ans += (1 << i), now = son;
        else now = tree[now][(x >> i) & 1];
    }
    return ans;
}

void dfs11(int x, int y, int sum, int num)
{
    if(num == n) {
        v11[x].push_back(sum ^ a[x][y]);
        return ;
    }
    if(x + 1 <= n) dfs11(x + 1, y, sum ^ a[x + 1][y], num + 1);
    if(y + 1 <= n) dfs11(x, y + 1, sum ^ a[x][y + 1], num + 1);
}

void dfsnn(int x, int y, int sum, int num)
{
    if(num == n) {
        vnn[x].push_back(e ^ sum);
        return ;
    }
    if(x - 1 >= 1) dfsnn(x - 1, y, sum ^ a[x - 1][y], num + 1);
    if(y - 1 >= 1) dfsnn(x, y - 1, sum ^ a[x][y - 1], num + 1);
}

signed main()
{
    scanf("%d %d", &n, &e);
    for(int i = 1; i <= n; ++ i) {
        for(int j = 1; j <= n; ++ j) {
            scanf("%d", &a[i][j]);
        }
    }

    dfs11(1, 1, a[1][1], 1);
    dfsnn(n, n, a[n][n], 1);

    int ans = 0;
    for(int i = 1; i <= n; ++ i) {
        memset(tree, 0, sizeof tree);
        cnt = 1;
        for(int j = 0; j < v11[i].size(); ++ j) {
            add(v11[i][j]);
        }
        for(int j = 0; j < vnn[i].size(); ++ j) {
            ans = max(ans, query(vnn[i][j]));
        }
    }

    printf("%d\n", ans);

    return 0;
}

/*

  Rejoicing in hope, patient in tribulation .

*/