#include <iostream>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <complex>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <bitset>
#include <ctime>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <cassert>
#include <cstddef>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <sstream>
#include <fstream>
#include <functional>

using namespace std;
#define REP(i, n) for (int (i) = 0; (i) < (n); (i)++)
#define FOR(i, a, b) for (int (i) = (a); (i) < (b); (i)++)
#define RREP(i, a) for(int (i) = (a) - 1; (i) >= 0; (i)--)
#define FORR(i, a, b) for(int (i) = (a) - 1; (i) >= (b); (i)--)
#define DEBUG(C) cerr << #C << " = " << C << endl;
using LL = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<LL>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using PII = pair<int, int>;
using PDD = pair<double, double>;
using PLL = pair<LL, LL>;
using VPII = vector<PII>;
template<typename T> using VT = vector<T>;
#define ALL(a) begin((a)), end((a))
#define RALL(a) rbegin((a)), rend((a))
#define SORT(a) sort(ALL((a)))
#define RSORT(a) sort(RALL((a)))
#define REVERSE(a) reverse(ALL((a)))
#define MP make_pair
#define FORE(a, b) for (auto &&a : (b))
#define EB emplace_back
#define GREATER(T) T, VT<T>, greater<T>
template<typename T> inline bool chmax(T &a, T b){if (a < b){a = b;return true;}return false;}
template<typename T> inline bool chmin(T &a, T b){if (a > b){a = b;return true;}return false;}

const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;

void solve() {
    int N, K;
    cin >> N >> K;
    VI a(N);
    REP(i, N) {
        cin >> a[i];
    }
    SORT(a);

    map<int, int> mp;
    FORE(e, a) mp[e]++;

    LL ans = 0;
    bool end = false;
    int cnt = 0;
    while (!end && cnt < K) {
        for (int i = 0; ; i++) {
            if (mp.count(i) == 0) {
                if (i == 0) {
                    end = true;
                }
                ans += i;
                break;
            }
            if (--mp[i] == 0) {
                mp.erase(i);
            }
        }
        cnt++;
    }

    cout << ans << endl;
}

int main(void) {
#ifndef ONLINE_JUDGE
    const auto in_stream = freopen("../in.txt", "r", stdin);
    if (in_stream == nullptr) {
        cerr << "ERROR!" << endl;
        return 1;
    }
#endif

    solve();

#ifndef ONLINE_JUDGE
    fclose(in_stream);
#endif
}

#include<bits/stdc++.h>
using namespace std;
using namespace std::chrono; 
const int mod=1e9+7;
const int mex=2002;
#define ll long long 
#define test int t;cin>>t;while(t--)
#define fast  ios_base::sync_with_stdio(false);cin.tie(NULL);
#define fo(i,a,n) for(int i=a;i<n;i++)
#define rfo(i,a,b) for(int i=a;i>=b;i--)
#define bg begin()
#define en end()
#define fi first
#define se second
#define ub upper_bound
#define lb lower_bound
#define pb push_back
#define veci vector<int>
#define veclli vector<long long int> 
#define all(x) x.begin(),x.end()
#define sci(x) scanf("%d",&x);
#define scc(x) scanf("%c",&x);
#define scs(x) scanf("%s",x);
#define debug(arr,n) for(int i=0;i<n;i++) printf("%d ",arr[i]);
#define sz(x) x.size()
#define loop(x) for(auto it=x.begin();it!= x.end();it++)
#define int long long
signed main()
{
    int n,k;
    cin>>n>>k;
    map<int,int> mp;
    int a[n];
    fo(i,0,n)
    {cin>>a[i];
    mp[a[i]]++;
    }
    int bx=k,ans=0;
    fo(i,0,n+1)
    {
        bx=min(bx,mp[i]);
        ans+=bx;
    }
    cout<<ans<<endl;

}
