#include<bits/stdc++.h>
using namespace std;


int solve(const vector<int>& v, int x){
	int n = v.size();
	int k = 0;
	int ans = 0;
	for(int i=n-1; i>k; --i){
		while(k < i && v[i]+v[k] <= x)
			k++;
		if(k < i)
			ans++;
		k++;
	}
	return ans;
}

int main(){
	int n, m, x;
	cin >> n >> m >> x;
	vector<int> v(n-1);
	for(int i=0; i<n-1; ++i)
		cin >> v[i];
	
	sort(v.begin(), v.end());

	int left = 0;
	int right = n - 1;
	while(left < right){
		int mid = (left + right) / 2;
		int y = v[mid];
		v.erase(v.begin() + mid);

		if(solve(v, x + y) < m)
			right = mid;
		else
			left = mid + 1;
		
		v.insert(v.begin() + mid, y);
	}

	if(left == n - 1)
		cout << -1 << endl;
	else
		cout << v[left] << endl;

	return 0;
}