#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}
inline double time() {
    return static_cast<long double>(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count()) * 1e-9;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n,w; cin >> n >> w;
    int m = 13;
    vector<int> cnt(m);
    for (int i = 0; i < n; ++i) {
        int a; cin >> a; a -= 1;
        cnt[a] += 1;
    }
    vector<int> dp(1<<m, 1e9);
    vector<int> sum(1<<m);
    for (int i = 0; i < (1<<m); ++i) {
        for (int j = 0; j < m; ++j) {
            if ((1<<j)&i) sum[i] += cnt[j];
        }
    }
    dp[0] = 0;
    for (int i = 1; i < (1<<m); ++i) {
        for (int j = 0; j <= i; ++j) {
            if ((i&j) == j) {
                int k = (i^j);
                if (sum[k] <= w) {
                    dp[i] = min(dp[i], dp[j]+1);
                }
            }
        }
    }
    cout << dp.back() << endl;
}