#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("-ffloat-store")
using namespace std;
clock_t time_p = clock();
void aryanc403() {}
const long long int INF = 3e9;
long long int seed;
mt19937 rng(seed = chrono::steady_clock::now().time_since_epoch().count());
inline long long int rnd(long long int l = 0, long long int r = INF) {
  return uniform_int_distribution<long long int>(l, r)(rng);
}
class CMP {
 public:
  bool operator()(pair<long long int, long long int> a,
                  pair<long long int, long long int> b) {
    return !(a.first < b.first || (a.first == b.first && a.second <= b.second));
  }
};
void add(map<long long int, long long int> &m, long long int x,
         long long int cnt = 1) {
  auto jt = m.find(x);
  if (jt == m.end())
    m.insert({x, cnt});
  else
    jt->second += cnt;
}
void del(map<long long int, long long int> &m, long long int x,
         long long int cnt = 1) {
  auto jt = m.find(x);
  if (jt->second <= cnt)
    m.erase(jt);
  else
    jt->second -= cnt;
}
bool cmp(const pair<long long int, long long int> &a,
         const pair<long long int, long long int> &b) {
  return a.first < b.first || (a.first == b.first && a.second < b.second);
}
const long long int mod = 1000000007L;
long long int T, n, i, j, k, in, cnt, l, r, u, v, x, y;
long long int m;
string s;
vector<long long int> a, b;
map<long long int, long long int> mm;
long long int fnd(long long int x, long long int n) {
  long long int i;
  long long int cnt = 0;
  for (i = 0; i < (n); ++i) cnt += (a[i] <= x);
  return cnt;
}
void upd(long long int x, long long int v) {
  x++;
  while (x <= INF) {
    mm[x] += v;
    x += x & (-x);
  }
}
long long int query(long long int x) {
  x++;
  long long int cnt = 0;
  while (x > 0) {
    cnt += mm[x];
    x -= x & (-x);
  }
  return cnt;
}
int main(void) {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  {
    long long int t;
    cin >> n >> t;
    a.clear();
    a.reserve(n);
    a.push_back(INF + 1);
    for (i = (1); i <= (n); ++i) {
      cin >> in;
      a.push_back(max(0LL, in - i));
    }
    n++;
    b = a;
    b.push_back(0);
    sort(begin(b), end(b));
    b.erase(unique(begin(b), end(b)), b.end());
    for (auto x : a) upd(x, 1);
    long long int ans = 0;
    for (auto x : b) {
      while (n >= 1 && n > t - x) {
        n--;
        upd(a[n], -1);
      }
      ans = max(ans, query(x));
    }
    cout << ans << "\n";
  }
  aryanc403();
  return 0;
}
