#include using namespace std; #define FOR(i,a,b) for(int i=(int)(a);i<(int)(b);i++) #define RFOR(i,a,b) for(int i=(int)(b)-1;i>=(int)(a);i--) #define REP(i,n) FOR(i,0,n) #define RREP(i,n) RFOR(i,0,n) #define LL long long #define INF INT_MAX/3 const double EPS = 1e-14; const double PI = acos(-1.0); int main(){ int n, x; int m = 1e5; cin >> n >> x; int a; vector v(m+2); REP (i, m + 1) v[i] = 0; REP (i, n) { cin >> a; v[a]++; } LL ans = 0; REP (i, m + 1) { if (x - i <= m) ans += v[i] * v[x - i]; } cout << ans << endl; }