#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#define debug(...) fprintf(stderr, ##__VA_ARGS__)
#else
#define endl "\n"
#define debug(...) void(0)
#endif
using LL = long long;
int n, m, a[50010];
bitset<50010> bs[50010], pre[50010];
int main() {
#ifndef LOCAL
  cin.tie(nullptr)->sync_with_stdio(false);  
#endif
  cin >> n >> m;
  for (int i = 1, x; i <= n; i++) cin >> x, a[x] = i;
  bitset<50010> tmp;
  for (int x = n; x >= 1; x--) {
	  int i = a[x];
	  bs[i] = tmp >> i;
	  tmp[i] = true;
  }
  LL ans = 0;
#ifdef LOCAL
  for (int i = 1; i <= n; i++) {
	  for (int j = 0; j < n; j++) debug("%d", (int)bs[i][j]);
	  debug("\n");
  }
#endif
  for (int i = m; i <= n; i += m) {
	  pre[i - 1].set();
	  for (int j = i; j <= n && j <= i + m; j++) pre[j] = pre[j - 1] & bs[j - 1];
	  bitset<50010> now = bs[i];
	  for (int j = i; j > i - m; j--) {
		  now &= bs[j];
		  if (j + m <= n + 1) ans += (now & pre[j + m]).count();
	  }
  }
  cout << ans << endl;
  return 0;
}