#include <bits/stdc++.h>
#pragma GCC optimize("Ofast,no-stack-protector,unroll-loops,fast-math,O3")
using namespace std;
long long powmod(long long a, long long b, long long mod) {
  if (b == 0 || a == 1) {
    if (mod == 1)
      return 0;
    else
      return 1;
  }
  if (b % 2 == 0) {
    long long k = powmod(a, b / 2, mod);
    return (k * k) % mod;
  } else {
    long long k = powmod(a, b / 2, mod);
    return ((k * k) % mod * a) % mod;
  }
}
long long gcd(long long a, long long b) {
  if (a == 0) return b;
  if (b == 0) return a;
  if (a > b)
    return gcd(a % b, b);
  else
    return gcd(b % a, a);
}
long long prime(long long p) {
  if (p < 4) return true;
  if (p % 2 == 0) return false;
  if (p % 3 == 0) return false;
  for (long long i = 5; i * i <= p; i += 6) {
    if (!(p % i)) return i;
    if (!(p % (i + 2))) return false;
  }
  return true;
}
long long inv(long long a, long long mod) { return powmod(a, mod - 2, mod); }
void solve(long long ppppppppp = 1) {
  long long a, k, x;
  cin >> a >> k >> x;
  long long m[a];
  long long min1 = a;
  for (long long i = 0; i < a; i++) cin >> m[i];
  for (long long i = 0; i < a - 1; i++) {
    if (m[i] == x && m[i + 1] == x) {
      vector<long long> cur;
      for (long long t = 0; t < i; t++) cur.push_back(m[t]);
      cur.push_back(x);
      for (long long t = i; t < a; t++) cur.push_back(m[t]);
      for (long long i = 1; i <= 100; i++) {
        vector<long long> new_1;
        for (long long j = 0; j < cur.size(); j++) {
          if (j < cur.size() - 2 && cur[j] == cur[j + 1] &&
              cur[j] == cur[j + 2])
            while (j < cur.size() && cur[j + 1] == cur[j]) j++;
          else
            new_1.push_back(cur[j]);
        }
        cur = new_1;
        min1 = min(min1, (long long)cur.size());
      }
    }
  }
  cout << a - min1;
  return;
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long tututu;
  tututu = 1;
  for (long long qwerty = 0; qwerty < tututu; qwerty++) solve();
  return 0;
}
