#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef pair<ll, ll> P;
typedef vector<ll> VI;
typedef vector<VI> VVI;
const ll MOD = 1000000007;
const ll INF = 4611686018427387903;
#define REP(i, n) for (int i = 0; i < n; i++)
#define ALL(v) v.begin(), v.end()

int main(){
	int n; cin >> n;
	VI a(n); REP(i,n) cin >> a[i];
	REP(i,n-1){
		REP(j,n-i-1){
			a[j]=(a[j]+a[j+1])%MOD;
		}
	}
	cout << a[0] << endl;
	return 0;
}