#include <bits/stdc++.h> #define int long long using namespace std; int n,q; int x[1000006],f[1000006]; signed main () { cin >> n >> q; for (int i = 1;i <= n;i++) { cin >> x[i]; } while (q--) { int a,b; cin >> a >> b; for (int i = 1;i <= n;i++) { f[i] = (x[i] ^ a) - b; } int ans = -1; for (int i = 1;i < n;i++) { if (f[i] * f[i + 1] <= 0) { ans = i; break; } } cout << ans << endl; } }