#pragma GCC optimize ("O3")
#pragma GCC target ("avx2")
#include <bits/stdc++.h>
using namespace std;

const int N=5e4+100;

int32_t p[N];
int32_t cnt[N],ans[N];

void iter(int32_t i, int32_t lim, int32_t m) {
    int32_t d = 1;
    for (; d <= lim; d++) {
        bool ok = p[i] < p[d + i];
        cnt[d] = (cnt[d] + 1) * ok;
        ans[d] += (cnt[d] >= m);
    }
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);

    int32_t n,m;
    cin >> n >> m;

#if 0 // real use
    for (int32_t i = 0; i < n; i++)
        cin >> p[i];
#else // random test
    for (int32_t i = 0; i < n; i++)
        p[i] = i;
    mt19937 rng;
    shuffle(p, p + n, rng);
#endif

    for (int32_t i = 0; i < n; i++)
        iter(i, min(n - m, n - i - 1), m);
    cout << accumulate(ans, ans + n, 0LL);
}