#pragma GCC optimize("Ofast")

#include <bits/stdc++.h>
#ifdef dbg
#define D(...) fprintf(stderr, __VA_ARGS__)
#define DD(...) D("[Debug] "#__VA_ARGS__ " = "), \
              debug_helper::debug(__VA_ARGS__), D("\n")
#include "C:\Users\wsyear\Desktop\OI\templates\debug.hpp"
#else
#define D(...) ((void)0)
#define DD(...) ((void)0)
#endif
#define rep(i, j, k) for (int i = (j); i <= (k); ++i)
#define per(i, j, k) for (int i = (j); i >= (k); --i)
#define SZ(v) int((v).size())
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second
using ll = long long;
using pii = std::pair<int, int>;
using pll = std::pair<ll, ll>;

template<class T> void chkmn(T &x, T y) { if (y < x) x = y; }
template<class T> void chkmx(T &x, T y) { if (y > x) x = y; }

using namespace std;

const int maxn = 50010;

bitset<maxn> f[maxn], o, cur, t[maxn << 2], tmp;
int n, m, a[maxn], pos[maxn];

#define mid ((l + r) >> 1)

void upd(int c, int l, int r, int x, int y) {
  if (l == x && r == y) return t[c] &= tmp, void();
  if (y <= mid) upd(c << 1, l, mid, x, y);
  else if (x > mid) upd(c << 1 | 1, mid + 1, r, x, y);
  else upd(c << 1, l, mid, x, mid), upd(c << 1 | 1, mid + 1, r, mid + 1, y);
}

void solve(int c, int l, int r) {
  if (l == r) return f[l] &= t[c], void();
  t[c << 1] &= t[c], t[c << 1 | 1] &= t[c];
  solve(c << 1, l, mid), solve(c << 1 | 1, mid + 1, r);
}

#undef mid

int main() {
  cin.tie(nullptr) -> ios::sync_with_stdio(false);
  cin >> n >> m;
  rep (i, 1, n) cin >> a[i];
  rep (i, 1, n - m) o.set(i);
  rep (i, 1, n - m) f[i] = o, o.reset(n - m - i + 1);
  rep (i, 1, n << 2) t[i].set();
  rep (i, 1, n) pos[a[i]] = i;
  cur.set();
  rep (i, 1, n) {
    cur.reset(pos[i]);
    tmp = cur >> pos[i];
    // rep (p, max(1, pos[i] - m + 1), pos[i]) f[p] &= tmp;
    upd(1, 1, n, max(1, pos[i] - m + 1), pos[i]);
  }
  solve(1, 1, n);
  ll ans = 0;
  rep (i, 1, n) ans += f[i].count();
  cout << ans << '\n';
}