package chelper;

import java.util.Arrays;
import java.util.Comparator;
import java.util.TreeSet;

import io.InputReader;
import io.OutputWriter;
import misc.ComparableCouple;
import misc.SimpleSavingChelperSolution;


public class D extends SimpleSavingChelperSolution {

  public void solve(int testNumber, InputReader in, OutputWriter out) {
    wrapSolve(testNumber, in, out);
  }

  @Override
  public void solve(int testNumber) {
    int n = in.nextInt();
    int T = in.nextInt() - 1;

    n = Math.min(n, T);

    int[] a = in.nextIntArray(n);

    int initWait = Math.max(T - n, 0);
    int leftToWait = T - initWait;

    int[] needMore = new int[n];

    int[] stats = new int[n + 10];

    for (int i = 0; i < n; i++) {
      needMore[i] = Math.max(a[i] - (initWait + i + 1), 0);

      needMore[i] = Math.min(needMore[i], leftToWait + 1);

      stats[needMore[i]] += 1;
    }

    int cur = stats[0];
    int best = cur;

    for (int i = 1; i <= leftToWait; i++) {
      cur += stats[i];

      int removed = needMore[n - i];
      if (removed <= i) {
        cur--;
      }
      stats[removed]--;

      best = Math.max(best, cur);
    }

    out.println(best);
  }
}