import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.complex, std.container, std.math, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


enum MO = 10L^^9 + 7;

long power(long a, long e) {
  long x = a % MO, y = 1 % MO;
  for (; e; e >>= 1) {
    if (e & 1) y = (y * x) % MO;
    x = (x * x) % MO;
  }
  return y;
}

int N;
long C;
long[] A;

void main() {
  try {
    for (; ; ) {
      N = readInt();
      C = readLong();
      A = new long[N];
      foreach (i; 0 .. N) {
        A[i] = readLong();
      }
      
      auto f = new long[N + 1];
      f[0] = 1;
      foreach (i; 0 .. N) {
        foreach_reverse (j; 0 .. i + 1) {
          (f[j + 1] -= f[j] * A[i]) %= MO;
        }
      }
      debug {
        writeln("f = ", f);
      }
      
      auto g = new long[N];
      g[0] = 1;
      foreach (i; 1 .. N) {
        foreach (j; 0 .. i) {
          (g[i] -= f[i - j] * g[j]) %= MO;
        }
      }
      debug {
        writeln("g = ", g);
      }
      
      long[] mul(long[] a, long[] b) {
        auto c = new long[2 * N - 1];
        foreach (i; 0 .. N) foreach (j; 0 .. N) {
          (c[i + j] += a[i] * b[j]) %= MO;
        }
        foreach_reverse (i; N .. 2 * N - 1) {
          foreach (j; 1 .. N + 1) {
            (c[i - j] -= f[j] * c[i]) %= MO;
          }
        }
        return c[0 .. N];
      }
      
      auto x = new long[N];
      auto y = new long[N];
      if (N == 1) {
        x[0] = -f[1];
      } else {
        x[1] = 1;
      }
      y[0] = 1;
      for (long e = C; e; e >>= 1) {
        if (e & 1) {
          y = mul(y, x);
        }
        x = mul(x, x);
      }
      
      long ans;
      foreach (i; 0 .. N) {
        (ans += y[i] * g[i]) %= MO;
      }
      
      foreach (i; 0 .. N) {
        (ans -= power(A[i], C)) %= MO;
      }
      
      ans = (ans % MO + MO) % MO;
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}