#include<bits/stdc++.h>
using namespace std;
typedef long long ll;

int main(){
	int n; cin >> n;
	ll k; cin >> k;
	vector<ll> a(n), b(n);
	for (int i=0; i<n; i++){
		cin >> a[i];
		if (a[i] <= k){
			b[i] = a[i];
		}else{
			if (a[i] % 2 == 0){
				b[i] = 0;
			}else{
				b[i] = -1;
			}
		}
	}
	sort(b.begin(), b.end());
	reverse(b.begin(), b.end());
	ll ans = 0;
	for (int i=0; i<n; i++){
		if (i % 2 == 0){
			ans += b[i];
		}else{
			ans -= b[i];
		}
		ans += a[i];
	}
	ans /= 2;
	cout << ans << '\n';
}