#include <bits/stdc++.h>
using namespace std;

using i64 = long long;

signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    int n, m;
    cin >> n >> m;
    vector<int> p(n + 1), pos(n + 1);
    for(int i = 0; i < n; i++) {
        cin >> p[i];
        pos[p[i]] = i;
    }
    vector<bitset<50100>> f(n + 1);
    bitset<50100> now;
    for(int i = n; i; i--) {
        f[i] = now >> pos[i];
        now.set(pos[i]);
    }
    vector<bitset<50100>> pre(n + 1), suf(n + 1);
    for(int i = 1; i <= n; i++) {
        if(i % m == 0) {
            pre[i] = f[i];
        } else {
            pre[i] = pre[i - 1] & f[i];
        }
    }
    for(int i = n; i; i--) {
        if(i == n || i % m == m - 1) {
            suf[i] = f[i];
        } else {
            suf[i] = suf[i + 1] & f[i];
        }
    }
    int ans = 0;
    for(int i = 1; i + m - 1 <= n; i++) {
        ans += (suf[i] & pre[i + m - 1]).count();
    }
    cout << ans << '\n';
    return 0;
}