#include <bits/stdc++.h>
#define endl '\n'
#define int long long
#define x first
#define y second
#define pb push_back
using namespace std;
typedef pair<int, int> PII;

int n, w, cnt[14], ww[1 << 13], dist[1 << 13];
bool vis[1 << 13];
vector<int> g[1 << 13];

void dijkstra() {
    memset(dist, 0x3f, sizeof(dist));
    dist[0] = 0;
    priority_queue<PII> pq;
    pq.push( {0, 0} );
    while ( pq.size() ) {
        int u = pq.top().y;
        pq.pop();
        if (vis[u]) continue;
        vis[u] = 1;
        for (auto v : g[u]) {
            if (vis[v]) continue;
            dist[v] = min(dist[v], dist[u] + 1);
            pq.push( { -dist[v], v } );
        }
    }
}

void solve() {
    cin >> n >> w;
    for (int i = 1; i <= n; i++) {
        int a;
        cin >> a;
        cnt[a]++;
    }
    for (int i = 0; i < (1 << 13); i++) {
        for (int j = 1; j <= 13; j++) {
            if ( i & ( 1 << (j - 1) ) ) ww[i] += cnt[j];
        }
    }
    for (int i = 0; i < (1 << 13); i++) {
        for (int j = 0; j < (1 << 13); j++) {
            if ( (i & j) != i || i == j ) continue;
            if ( ww[j - i] <= w ) g[i].pb(j);
        }
    }
    dijkstra();
    cout << dist[(1 << 13) - 1] << endl;
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int t = 1;
    // cin >> t;
    while (t--) solve();
    return 0;
}