#include <bits/stdc++.h>
#include <inttypes.h>
using namespace std;
//#define  red uint64;
int main() {
    uint64_t n;
    cin >> n;

    uint64_t res = 0, a;
    cin >> res;
    for (uint64_t i = 1; i < n; i++) {
        cin >> a;
        res = res^a;
    }
    //cout << res%2 << endl;
    uint64_t ans = 0;
    if (res%2 == 1) {cout << 0 << endl; return 0;}


    for (uint64_t k = 1; k < n; k++) {
        uint64_t x = 1;
        uint64_t l = 1;
        for (uint64_t j = k+1; j <= n; j++) {
            x *= j;
            if (l <= n - k && x%l == 0) {
                x /= l; l++;
            }
        }

        //cout << "x = " <<x << endl;
        ans += x;
    }
    cout << ans << endl;

    return 0;
}