#include <bits/stdc++.h>
using namespace std;
long long n, fact[200001], a[200005];
long long power(long long a, long long b) {
  if (b == 0) return 1;
  long long p = power(a, b / 2);
  p = ((p % 1000000007) * (p % 1000000007)) % 1000000007;
  if (b & 1) {
    return (a * p) % 1000000007;
  }
  return p;
}
long long mod_inv(long long n, long long m) {
  long long div = power((fact[n - m] * fact[m]) % 1000000007, 1000000007 - 2);
  return (fact[n] * div) % 1000000007;
}
int main() {
  fact[0] = 1;
  for (int i = 1; i <= 200000; i++) {
    fact[i] = (fact[i - 1] * i) % 1000000007;
  }
  scanf("%lld", &n);
  for (int i = 0; i < n; i++) {
    scanf("%lld", &a[i]);
  }
  long long ans = 0;
  if (n % 4 == 0) {
    n = n - 2;
    n /= 2;
    for (int i = 0; i < n * 2 + 2; i++) {
      if (i & 1) {
        ans -= ((mod_inv(n, i / 2)) * a[i]) % 1000000007;
        ans = (ans + 1000000007) % 1000000007;
      } else {
        ans += ((mod_inv(n, i / 2)) * a[i]) % 1000000007;
        ;
        ans = (ans + 1000000007) % 1000000007;
      }
    }
  } else if (n % 4 == 1) {
    long long sz = n;
    n = n - 1;
    n /= 2;
    for (int i = 0; i < sz; i += 2) {
      ans += ((mod_inv(n, i / 2)) * a[i]) % 1000000007;
      ans = (ans + 1000000007) % 1000000007;
    }
  } else if (n % 4 == 2) {
    long long sz = n;
    n = n - 2;
    n /= 2;
    for (int i = 0; i < sz; i++) {
      ans += ((mod_inv(n, i / 2)) * a[i]) % 1000000007;
      ;
      ans = (ans + 1000000007) % 1000000007;
    }
  } else {
    long long sz = n;
    n = n - 3;
    n /= 2;
    ans = (a[0] * mod_inv(n, 0)) % 1000000007;
    for (int i = 1; i < sz; i++) {
      if (i & 1) {
        ans += (2 * (mod_inv(n, i / 2)) * a[i]) % 1000000007;
        ;
        ans = ans = (ans + 1000000007) % 1000000007;
      } else {
        ans +=
            ((mod_inv(n, i / 2) - mod_inv(n, (i / 2) - 1)) * a[i]) % 1000000007;
        ans = (ans + 1000000007) % 1000000007;
      }
    }
  }
  cout << ans << endl;
  return 0;
}
