197D

#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <fstream>
#include <ctime>
using namespace std;

#define TASK ""
#define INF 1e18
#define MOD 1000000007

vector < unsigned int > tree;

void build(int n) {
    int now = pow(2, n) - 1;
    while (now > 0) {
        if ((int(log2(now)) + 1) % 2 == n % 2) {
            tree[now] = tree[now * 2] | tree[now * 2 + 1];
        }
        else {
            tree[now] = tree[now * 2] ^ tree[now * 2 + 1];
        }
        now--;
    }
}

int update(int n, int pos, int v) {
    int now = pos + pow(2, n);
    tree[now] = v;
    now /= 2;
    while (now > 0) {
        if ((int(log2(now)) + 1) % 2 == n % 2) {
            tree[now] = tree[now * 2] | tree[now * 2 + 1];
        }
        else {
            tree[now] = tree[now * 2] ^ tree[now * 2 + 1];
        }
        now /= 2;
    }
    return tree[1];
}

int main() {

#ifdef _DEBUG
    freopen("debug.in", "r", stdin);
    freopen("debug.out", "w", stdout);
#else
    //freopen(TASK".in", "r", stdin);
    //freopen(TASK".out", "w", stdout);
    //freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
#endif // _DEBUG

    srand(time(0));
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cout.precision(9);

    int n, m, st, p, b;
    cin >> n >> m;
    st = pow(2, n);
    tree.resize(2 * st);
    for (int i = 0; i < st; i++) {
        cin >> tree[st + i];
    }
    build(n);
    for (int i = 0; i < m; i++) {
        cin >> p >> b;
        cout << update(n, p - 1, b) << "\n";
    }

    return 0;
}