// Hallelujah, praise the one who set me free
// Hallelujah, death has lost its grip on me
// You have broken every chain, There's salvation in your name
// Jesus Christ, my living hope
#include <bits/stdc++.h> 
using namespace std;

#define REP(i, s, e) for (int i = (s); i < (e); i++)
#define RREP(i, s, e) for (int i = (s); i >= (e); i--)
template <class T>
inline bool mnto(T& a, T b) {return b < a ? a = b, 1 : 0;}
template <class T>
inline bool mxto(T& a, T b) {return a < b ? a = b, 1: 0;}

typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
#define FI first
#define SE second
typedef pair<int, int> ii;
typedef pair<ll, ll> pll;
typedef tuple<int, int, int> iii;
#define ALL(_a) _a.begin(), _a.end()
#define SZ(_a) (int) _a.size()
#define pb push_back
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<ii> vii;
typedef vector<iii> viii;

#ifndef DEBUG
#define cerr if (0) cerr
#endif

const int INF = 1000000005;
const ll LINF = 1000000000000000005ll;
const int MAXN = 50005;

int n, m;
int p[MAXN], ip[MAXN];
bitset<MAXN> sp[MAXN];
ll ans;

bitset<MAXN> qry(int s, int e) {
    int k = 31 - __builtin_clz(e - s + 1);
    return sp[k][s] & sp[k][e - (1 << k) + 1];
}

int main() {
#ifndef DEBUG
    ios::sync_with_stdio(0), cin.tie(0);
#endif
    cin >> n >> m;
    REP (i, 0, n) {
        cin >> p[i];
        p[i]--;
        ip[p[i]] = i;
    }
    bitset<MAXN> base;
    RREP (i, n - 1, 0) {
        sp[i] = base >> ip[i];
        base[ip[i]] = 1;
    }
    int gk = 31 - __builtin_clz(m);
    REP (k, 1, gk + 1) {
        REP (i, 0, n - (1 << k - 1)) {
            sp[i] = sp[i] & sp[i + (1 << k - 1)];
        }
    }
    REP (l, 0, n - m + 1) {
        bitset<MAXN> cur = sp[l] & sp[l + m - (1 << gk)];
        /*
        cur.set();
        REP (i, l, l + m) {
            cur &= dp[i];
        }
        */
        ans += cur.count();
    }
    cout << ans << '\n';
    return 0;
}