#define F first
#define S second
#define rep(i,a,b) for(int i=a;!(a==b&&i!=b)&&((i<=b&&b>=a)||(i>=b&&a>=b));i+=(a<=b?1:-1))
#define pb push_back
#define Fbitl __builtin_ffs
#define bit1 __builtin_popcount
#include <iostream>
#include <math.h>
#include <algorithm>
#include <string.h>
#include <vector>
#include <queue>
#include <map>
#include <unordered_map>

using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<string, string> pss;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vii;
typedef vector<ll> vl;
typedef vector<vl> vvl;
bool visa[(int)1e6] ;
int main(){
   ios_base::sync_with_stdio(0);cin.tie(0);
   
   		ll n , k;
   		cin >> n >>k ;
   		vi x(n);
   		for(auto&i:x)cin>>i;
   		sort(x.begin(),x.end());
   		ll mnx = x[k-1] , ax = mnx ;
   		for ( int i = k-2 ; i >= 0 ; i-- ) {
   			ax--;
   			if ( ax >= x[i] ) continue;
   			else {
   				ll b = (x[i]-ax) ;
   				ax += b ;
   				mnx += b ;
   			}
   		}
   		cout << mnx ;
   return 0;
}