xs

scanf("%d %d", &w, &n);

for (int i = 1; i <= n; i++) {

    scanf("%d", &a[i]);

}
sort(a + 1, a + 1 + n);
for (int i = 1; i <= n; i++) {
    if (k[i] == 1)
        continue;
    int sum = 0, l = 0;
    for (int j = n; j >= i + 1; j--) {
        if (k[j] == 0)
            if (a[j] + a[i] <= w) {
                l = j;
                break;
            }
    }
    ans++;
    k[l] = 1;
    k[i] = 1;
}
printf("%d", ans);
return 0;