// Author: lycc
// 
// Problem: P10818 [EC Final 2020] Random Shuffle
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/P10818
// Memory Limit: 256 MB
// Time Limit: 1000 ms

#include <bits/stdc++.h>
#define int long long
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define pb emplace_back
#define For(i, x, y) for (int i = (x); i <= (y); i ++)
#define rep(i, x, y) for (int i = (x); i >= (y); i --)
#define pii pair<int, int>
#define all(v) v.begin(), v.end()
#define sz(v) (int)((v).size())
#define ull unsigned long long
#define ls (p << 1)
#define rs (p << 1 | 1)
#define mp make_pair
#define i128 __int128
#define db long double
#define vi vector< int >
#define mem(v, x) memset(v, x, sizeof(v))
#define A3 array< int, 3 >
#define A4 array< int, 4 >
#define vpii vector< pair< int, int > >
using namespace std;
mt19937_64 rnd(time(0));
template< typename T > void cmin(T &x, T y) { return x = min(x, y), void(); }
template< typename T > void cmax(T &x, T y) { return x = max(x, y), void(); }
int ksm(int x, int y, int p) {
    int v = 1; x %= p;
    while (y) v = 1ll * v * ((y & 1) ? x : 1) % p, x = 1ll * x * x % p, y >>= 1;
    return (v % p + p) % p;
}
void file() {
	freopen("1.in", "r", stdin);
	freopen("1.out", "w", stdout);
	return;
}
bool MemoryST;
const int N = 1e5 + 5;
const int mod = 998244353;
const long long INF = 1e18;
const int base = 13131;
using ll = long long;
int n, pos[N], res[N], a[N];
ull s[N][64];
ull I = 1;
ull val[64], b[64];
int val2[64];
void insert(ull x, int v) {
	rep (i, 63, 0) {
		if ((x >> i) & 1) {
			if (!val[i]) {
				val[i] = x; val2[i] = v; break;
			} else {
				x ^= val[i]; v ^= val2[i];
			}
		}
	}
	return;
}
ull work(ull x) {
    x ^= x << 13;
    x ^= x >> 7;
    x ^= x << 17;
    return x;
}
bool check(ull ans) {
	For (i, 1, n) {
		ans = work(ans);
		if (ans % i != res[i]) {
			return 0;
		}
	}
	return 1;
}
void Main() {
	cin >> n;
	For (i, 1, n) {
		cin >> a[i];
		pos[a[i]] = i;
	}
	rep (i, n, 1) {
		res[i] = pos[i] - 1;
		pos[a[i]] = pos[i];
		a[pos[i]] = a[i];
	}
	For (i, 0, 63) s[0][i] = I << i;
	For (i, 1, 50) {
		rep (j, 63, 13) s[i][j] = s[i - 1][j] ^ s[i - 1][j - 13];
		For (j, 0, 12) s[i][j] = s[i - 1][j];
		For (j, 0, 56) s[i][j] ^= s[i][j + 7];
		rep (j, 63, 17) s[i][j] ^= s[i][j - 17];
		int w = 1;
		while (i % (w * 2) == 0) w <<= 1;
		int maxn = __lg(w);
		For (j, 0, maxn - 1) {
			insert(s[i][j], ((res[i] % w) >> j) & 1);
		}
	}
	int cnt = 0;
	vi todo;
	For (i, 0, 63) {
		cnt += (val[i] != 0);
		if (val[i] == 0) todo.pb(i);
	}
	cerr << cnt << '\n';
	For (S, 0, (1 << 17) - 1) {
		ull ans = 0;
		For (i, 0, 16) {
			if ((S >> i) & 1) {
				b[todo[i]] = 1;
			} else {
				b[todo[i]] = 0;
			}
		}
		For (i, 0, 63) {
			if (val[i]) {
				b[i] = val2[i];
				For (j, 0, i - 1) {
					if ((val[i] >> j) & 1) {
						b[i] ^= b[j];
					}
				}
			}
			if (b[i]) ans |= I << i;
		}
		if (check(ans)) return cout << ans, void();
	}
	assert(0);
    return;
}
bool MemoryED;
signed main() {
	// file();
    ios :: sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    cerr << fixed << setprecision(6) << (&MemoryST - &MemoryED) / 1048576.0 << "MB\n";
    int TESTCNT = 1;
    // cin >> TESTCNT;
    while (TESTCNT --) Main();
    cerr << endl << 1e3 * clock() / CLOCKS_PER_SEC << "ms"; 
    return 0;
}