#include <iostream>
#include <vector>
#include <climits>

using namespace std;

int main() {
    int n, m;
    cin >> n >> m;

    vector<int> a(n);
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }

    // 初始化动态规划数组dp
    vector<vector<int>> dp(n + 1, vector<int>(m + 1, INT_MAX));
    vector<int> prefixXor(n + 1, 0);
    dp[0][0] = 0;

    for (int i = 1; i <= n; i++) {
        prefixXor[i] = prefixXor[i - 1] ^ a[i - 1];
    }

    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= min(i, m); j++) {
            for (int k = 0; k < i; k++) {
                dp[i][j] = min(dp[i][j], max(dp[k][j - 1], prefixXor[i] ^ prefixXor[k]));
            }
        }
    }

    cout << dp[n][m] << endl;

    return 0;
}