#include <bits/stdc++.h>
using namespace std;
int esq[1000010], dir[1000010], v[1000010];
int v1[1000010];
int tree_max[1000010], tree_min[1000010];
long long ans;
void update_max(int u, int pos) {
  while (u < 1000010) {
    tree_max[u] = max(tree_max[u], pos);
    u += (u & -u);
  }
}
void update_min(int u, int pos) {
  while (u < 1000010) {
    tree_min[u] = min(tree_min[u], pos);
    u += (u & -u);
  }
}
int query_max(int u) {
  int ans = -1;
  while (u) {
    ans = max(ans, tree_max[u]);
    u -= (u & -u);
  }
  return ans;
}
int query_min(int u) {
  int ans = 1e9;
  while (u) {
    ans = min(ans, tree_min[u]);
    u -= (u & -u);
  }
  return ans;
}
set<int> S;
vector<int> S1;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n, k;
  cin >> n >> k;
  k--;
  for (int i = 0; i < n; i++) {
    cin >> v[i];
    S.insert(v[i]);
  }
  for (auto &u : S) S1.push_back(u);
  for (int i = 0; i < n; i++) {
    v1[i] = (lower_bound(S1.begin(), S1.end(), v[i]) - S1.begin()) + 1;
  }
  for (int i = 1; i < 1000010; i++) tree_min[i] = n, tree_max[i] = -1;
  for (int i = 0; i < n; i++) {
    esq[i] = query_max(1000010 - (v1[i] + 1) - 1);
    update_max(1000010 - v1[i] - 1, i);
  }
  for (int i = n - 1; i >= 0; i--) {
    dir[i] = query_min(1000010 - v1[i] - 1);
    update_min(1000010 - v1[i] - 1, i);
  }
  for (int i = 0; i < n; i++) {
    int a = i - esq[i] - 1;
    int b = dir[i] - i - 1;
    long long x = (long long)v[i];
    if (a > b) swap(a, b);
    for (int i = 0; i <= a; i++) {
      int l1 = (a - i + k - 1) / k;
      if (l1 == 0) l1 = 1;
      int l2 = (a + b - i) / k;
      ans += (x * max(0, l2 - l1 + 1)) % 1000000007LL;
      if (ans >= 1000000007LL) ans -= 1000000007LL;
    }
  }
  cout << ans << "\n";
  return 0;
}
