#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i=0;i<n;i++)

int main() {
	int n, x;
	cin >> n >> x;
	vector<int> a(n);
	int xs = 0, ns = 0, ans = 0;
	for (int i = 0; i < n; i++) {
		cin >> a[i];
		xs += a[i]/x;
		ns += a[i]%x;
	}

	bool g = true;
	while (g) {
		if (xs > 0 && ns > 0) {
			xs--;
			ns--;
			ans++;
		} else if (xs > 1 && ns == 0) {
			xs -= 2;
			ns += 2;
			ans++;
		} else {
			g = false;
		}
	}

	cout << ans << "\n";

	return 0;
}