#include<iostream>
#include<algorithm>
using namespace std;

#define ll long long
const int MAXN = 2 * 1e5 + 5;
const ll INF = MAXN * MAXN + 5;
int n, k;
int a[MAXN];

bool check(ll x, int v){
    while(v --){
        int pos = lower_bound(a + 1, a + n + 1, x) - a;
        if(pos > n || a[pos] > x){
            pos --;
        }
        x -= pos;
    }
    return x < 1;
}

int main(){
	freopen("ntarsis_set.in", "r", stdin);
	freopen("ntarsis_set.out", "w", stdout);
    cin >> n >> k;
    for(int i = 1;i <= n;i ++){
        cin >> a[i];
    }
    ll l = 1, r = INF;
    ll res = 1;
    while(l <= r){
        ll mid = (l & r) + ((l ^ r) >> 1);
        if(check(mid, k)){
            l = mid + 1;
        }
        else{
            res = mid;
            r = mid - 1;
        }
    }
    cout << res << '\n';
    return 0;
}