import java.util.*; import java.io.*; public class Main { public static void main(String[] args) throws Exception { FastScanner sc = new FastScanner(System.in); long mod = (long)Math.pow(10,9)+7; int n = sc.nextInt(); long k = sc.nextInt(); long ans = 0; for(int i = 0; i < n; i++){ ans += (sc.nextLong()*(k+1)) % mod; ans %= mod; } System.out.println(ans); } } class FastScanner { private BufferedReader reader = null; private StringTokenizer tokenizer = null; public FastScanner(InputStream in) { reader = new BufferedReader(new InputStreamReader(in)); tokenizer = null; } public String next() { if (tokenizer == null || !tokenizer.hasMoreTokens()) { try { tokenizer = new StringTokenizer(reader.readLine()); } catch (IOException e) { throw new RuntimeException(e); } } return tokenizer.nextToken(); } public String nextLine() { if (tokenizer == null || !tokenizer.hasMoreTokens()) { try { return reader.readLine(); } catch (IOException e) { throw new RuntimeException(e); } } return tokenizer.nextToken("\n"); } public long nextLong() { return Long.parseLong(next()); } public int nextInt() { return Integer.parseInt(next()); } public double nextDouble() { return Double.parseDouble(next()); } public String[] nextArray(int n) { String[] a = new String[n]; for (int i = 0; i < n; i++) a[i] = next(); return a; } public int[] nextIntArray(int n) { int[] a = new int[n]; for (int i = 0; i < n; i++) a[i] = nextInt(); return a; } public long[] nextLongArray(int n) { long[] a = new long[n]; for (int i = 0; i < n; i++) a[i] = nextLong(); return a; } }