#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>

#define REP(i,s,n) for(int i=(int)(s);i<(int)(n);i++)

using namespace std;
typedef long long int ll;
typedef vector<int> VI;
typedef pair<int, int> PI;
const double EPS=1e-9;


const int N = 10010;
int a[N];
const int mod = 1e9 + 7;
int n, k;

/* k is small */
void small() {
  a[n] = 0;
  REP(i, 0, n) {
    a[n] += a[i];
  }
  REP(i, n, k) {
    int c = i % (n + 1);
    ll s = 2 * a[c];
    s += mod - a[(i + n) % (n + 1)];
    a[i] = s % mod;
  }
  cout << a[(k - 1) % (n + 1)] << endl;
}

void large() {
}

int main(void){
  cin >> n >> k;
  REP(i, 0, n) {
    cin >> a[i];
  }
  if (n >= 31) {
    small();
    return 0;
  }
  large();
}