#include <bits/stdc++.h>
#define ll long long
#define all(x) x.begin(),x.end()
#define answer(x) cout << (x ? "YES\n" : "NO\n")
#define test ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); int T; cin >> T; while(T--)
#define go ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define F first
#define S second
using namespace std;

const int N = 200100; 
ll n, d, a[N]; 

int main()
{
	ll ans = 0; 
	
	cin >> n >> d; 
	for(int i=1 ; i<=n;i ++) cin >> a[i], ans = (a[i] == d); 
	
	
	if(d == 0)
		for(int i=1 ;i<=n; i++) if(a[i] == 0)
		{
			int j = i; 
			ll l_ans = 0; 
			while(i <= n && a[i] == 0)
				l_ans ++, i ++; 
			
			ans = max(ans, l_ans); 
			i --; 
		}
	
	cout << ans; 
}