#pragma GCC optimize ("Ofast")
#pragma GCC target ("sse4")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll, ll> pll;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define all(x) begin(x),end(x)

#define forn(i, n) for (int i = 0; i < n; ++i)
#define rforn(i, n) for (int i = n - 1; i >= 0; --i)

const int N = 2e5 + 5, M = 1e9 + 7; // 998244353
const int dx[]{0, 1, 0, -1}, dy[]{1, 0, -1, 0};
const ll INF = 1e18 + 10LL;
const ld PI = 4.0 * atan((ld) 1.0), EPS = 1e-6;
const char nl = '\n';

template< typename T > inline T gcd(T a, T b) { return b == 0 ? a : gcd(b, a % b); }
template< typename T> inline T lcm(T a, T b) { return a / gcd(a, b) * b; }
template <class T> void ckmin(T& a, T b) {a = min(a, b);}
template <class T> void ckmax(T& a, T b) {a = max(a, b);}
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

string YN(bool x) { return x ? "YES" : "NO"; }

void solve(int tcn) {
	int n;
	cin >> n;
	vector<int> a(n);
	forn(i, n)
		cin >> a[i];
	while (a.size() > 1) {
		vector<int> b(a.size() - 1);
		forn(i, a.size() - 1) {
			b[i] = a[i] + a[i + 1];
			b[i] %= M;
		}
		a = b;
	}
	cout << a[0] % M << nl;
}

int main() {
	ios_base::sync_with_stdio(0); cin.tie(0);

	int t = 1; //cin >> t;
	for (int i = 1; i <= t; ++i) {
		solve(i);
	}
	return 0;
}