#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;

#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define rep(i,a,b) for (int i = (a); i < (b); ++i)

mt19937 rng(random_device{}());

int main()
{
    cin.tie(0)->sync_with_stdio(0);

    int n, x;
    cin >> n >> x;
    vi a(n), b(n);
    rep(i,0,n) cin >> a[i];

    rep(i,0,n) {
        b[i] = x - a[i];
    }

    map<int,int> freq;
    rep(i,0,n) {
        freq[a[i]]++;
        freq[b[i]]++;
    }

    int ans = 0;
    for(auto x : freq) {
        if(x.se >= 2) ans += x.se-1;
    }

    cout << ans << endl;

    return 0;
}