#include <bits/stdc++.h>
int temp[500000], a[500000], indices[500000], increments[500000],
    previous_appearance[500000], numbers_equal_c[500000];
void mergesort(int Array[], int indices[], int first, int last) {
  if (first == last) return;
  int middle = (first + last) / 2;
  mergesort(Array, indices, first, middle);
  mergesort(Array, indices, middle + 1, last);
  int i, j, k;
  for (i = first, j = first, k = middle + 1; i <= last; i++) {
    if (j == middle + 1)
      temp[i] = indices[k++];
    else if (k == last + 1)
      temp[i] = indices[j++];
    else if (Array[indices[k]] < Array[indices[j]])
      temp[i] = indices[k++];
    else
      temp[i] = indices[j++];
  }
  for (i = first; i <= last; i++) {
    indices[i] = temp[i];
  }
}
int main() {
  int n, i, one_counter = 0, c, maximum_increament = 0, number_equal_to_c = 0;
  scanf("%d %d", &n, &c);
  for (i = 0; i < n; i++) {
    scanf("%d", &a[i]);
    indices[i] = i;
    previous_appearance[i] = -1;
    numbers_equal_c[i] = 0;
    increments[i] = 0;
  }
  mergesort(a, indices, 0, n - 1);
  for (i = 1; i < n; i++) {
    if (a[indices[i]] == a[indices[i - 1]]) {
      previous_appearance[indices[i]] = indices[i - 1];
    }
  }
  for (i = 0; i < n; i++) {
    if (a[i] == c) {
      number_equal_to_c++;
    } else {
      if (previous_appearance[i] == -1 ||
          increments[previous_appearance[i]] - number_equal_to_c +
                  numbers_equal_c[previous_appearance[i]] + 1 <=
              0)
        increments[i] = 1;
      else
        increments[i] = increments[previous_appearance[i]] - number_equal_to_c +
                        numbers_equal_c[previous_appearance[i]] + 1;
      if (maximum_increament < increments[i])
        maximum_increament = increments[i];
    }
    numbers_equal_c[i] = number_equal_to_c;
  }
  printf("%d", number_equal_to_c + maximum_increament);
  return 0;
}
