#include <bits/stdc++.h>
#define all(a) begin(a), end(a)
#define int long long

using namespace std;

const int N = 5e4 + 11;

typedef bitset<N> BIT;

int a[N];
BIT c[N], pf[N], sf[N];
void solve(){
	int n, m; cin >> n >> m;
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	BIT I; for (int i = 0; i < N; i++) I[i] = 1;
	BIT cur;
	vector<pair<int, int>> b;
	for (int i = 0; i < n; i++) {
		b.push_back({a[i], i});
	}
	sort(b.begin(), b.end(), greater<pair<int, int>>());
	for (auto [val, idx] : b) {
		c[idx] = (I << (idx + 1)) & cur;
		cur[idx] = 1;
	}

	for (int i = 0; i < n; i++) {
		if (i % m) pf[i] = c[i] & pf[i - 1];
		else pf[i] = c[i];

		if (i % m != m - 1) sf[i] = c[i] & sf[i + 1];
		else sf[i] = c[i];
	}

	int ans = 0;
	for (int i = 0; i <= n - m; i++) {
		ans += (pf[i] & sf[i]).count();
	}
	cout << ans << '\n';
}

int32_t main(){
#ifndef LOCAL
	cin.tie(0); cout.tie(0)->sync_with_stdio(false);
#endif
	int t = 1;
	// cin >> t;
	while (t--) {
		solve();
	}
}