ABC407D

#include <assert.h>
#include <bits/stdc++.h>
using namespace std;
#ifndef __DEBUG__
#define dbg(...) 42
#endif
template <class T>
using mpq = priority_queue<T, vector<T>, greater<T>>;

namespace rngs = std::ranges;
using ll = long long;
using a2l = array<ll, 2>;
using pll = pair<ll, ll>;
using vl = vector<ll>;

int main(int argc, char **argv) {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    ll h, w, xall = 0;
    cin >> h >> w;
    vector<vl> a(h, vl(w));
    for (auto &row : a)
        for (auto &col : row)
            cin >> col, xall ^= col;

    vector<vl> mark(h, vl(w));
    ll ans = 0;
    ll cnt = 0;
    auto dfs = [&](auto &&self, ll x, ll y, ll acc) -> void {
        cnt += 1;
        if (y >= w)
            y = 0, x += 1;
        if (x >= h) {
            ans = max(ans, acc);
            return;
        }

        if (mark[x][y] == 0) {
            self(self, x, y + 1, acc);
            if (x + 1 < h && !mark[x + 1][y]) {
                mark[x][y] = mark[x + 1][y] = 1;
                self(self, x, y + 1, acc ^ a[x][y]);
                mark[x][y] = mark[x + 1][y] = 0;
            }
            if (y + 1 < w && !mark[x][y + 1]) {
                mark[x][y] = mark[x][y + 1] = 1;
                self(self, x, y + 1, acc ^ a[x][y]);
                mark[x][y] = mark[x][y + 1] = 0;
            }
        } else
            self(self, x, y + 1, acc ^ a[x][y]);
    };

    dfs(dfs, 0, 0, xall);
    cout << ans << '\n';
    dbg(cnt);

    return 0;
}