#include <bits/stdc++.h>
using namespace std;
const int N = 5e4 + 5;

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0); cout.tie(0);

	int n, m; cin >> n >> m; 
	int idxval[n], validx[n];
	for (int i = 0; i < n; i++) {
		cin >> idxval[i];
		validx[idxval[i]] = i;
	}

	bitset<N> moveback[n]; // if element at idx i ok w moving back by j
	bitset<N> occ; // idx of all visited values
	for (int i = n; i; i--) {
		int idx = validx[i];
		moveback[idx] = occ >> idx;
		occ[idx] = 1; // mark cur value as visited
	}

	bitset<N> sufok[n], prefok[n];
	for (int i = n-1; i >= 0; i--) {
		if (i % m == m-1 || i == n-1) sufok[i] = moveback[i];
		else sufok[i] = (sufok[i+1]&moveback[i]);
	}
	for (int i = 0; i < n; i++) {
		if (i % m == m-1 || i == 0) prefok[i] = moveback[i];
		else prefok[i] = (prefok[i-1]&moveback[i]);
	}

	int ans = 0;
	for (int i = 0; i + m - 1 < n; i++) {
		ans += (prefok[i+m-1]&sufok[i]).count();
	}
	cout << ans << "\n";
}