#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main() {
	int w, n;
	cin >> w >> n;
	vector<int> s(n);
	for (int i = 0; i < n; i++)cin >> s[i];
	int res = 0;
	sort(s.begin(), s.end());
	int p1 = 0;
	int p2 = n - 1;
	while (p1 < p2) {
		if (s[p1] + s[p2] > w) {
			res++;
			p2--;
		}
		else {
			res++;
			p1++;
			p2--;
		}
	}if (p1 == p2)res++;
	cout << res << endl;
	return 0;
}