#include <bits/stdc++.h>
using namespace std;
int main() {
int n; cin >> n;
vector<int> arr(n);
long long ans = 0, x;
for(int i=0;i<n;i++) cin >> arr[i];
if (n % 2 == 0) {
cout << 0;
return 0;
}
for(int i=0;i<n;i+=2){
ans ^= arr[i];
}
cout << ans % 1000000007;
}
I2luY2x1ZGUgPGJpdHMvc3RkYysrLmg+CnVzaW5nIG5hbWVzcGFjZSBzdGQ7CgppbnQgbWFpbigpIHsKCWludCBuOyBjaW4gPj4gbjsKCXZlY3RvcjxpbnQ+IGFycihuKTsKICAgIGxvbmcgbG9uZyBhbnMgPSAwLCB4OwogICAgCiAgICBmb3IoaW50IGk9MDtpPG47aSsrKSBjaW4gPj4gYXJyW2ldOwoKICAgIGlmIChuICUgMiA9PSAwKSB7CiAgICAgICAgY291dCA8PCAwOwogICAgICAgIHJldHVybiAwOwogICAgfQoKICAgIGZvcihpbnQgaT0wO2k8bjtpKz0yKXsKICAgICAgICBhbnMgXj0gYXJyW2ldOwogICAgfQogICAgY291dCA8PCBhbnMgJSAxMDAwMDAwMDA3Owp9