import java.io.*; import java.util.*; public class Main { static final int MOD = 1000000007; public static void main(String[] args) throws Exception { Scanner sc = new Scanner(); int n = sc.nextInt(); int[] current = new int[n]; for (int i = 0; i < n; i++) { current[i] = sc.nextInt(); } for (int i = 0; i < n - 1; i++) { int[] next = new int[n - i - 1]; for (int j = 0; j < n - i - 1; j++) { next[j] = (current[j] + current[j + 1]) % MOD; } current = next; } System.out.println(current[0]); } } class Scanner { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); StringTokenizer st = new StringTokenizer(""); StringBuilder sb = new StringBuilder(); public Scanner() throws Exception { } public int nextInt() throws Exception { return Integer.parseInt(next()); } public long nextLong() throws Exception { return Long.parseLong(next()); } public double nextDouble() throws Exception { return Double.parseDouble(next()); } public String next() throws Exception { while (!st.hasMoreTokens()) { st = new StringTokenizer(br.readLine()); } return st.nextToken(); } }