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

int main() {
    int N,K; cin >> N >> K;
    set<pair<int,long long>> S;
    priority_queue<pair<long long,int>> Q;
    for(int i=0; i<N; i++){
        int a; cin >> a;
        S.insert({i,a}),Q.push({a,i});
    }
    long long now = 0;
    for(int t=0; t<K; t++){
        while(true){
            if(Q.size() == 0){cout << "Impossible\n"; return 0;}
            auto [v,pos] = Q.top(); Q.pop();
            if(!S.count({pos,v})) continue;
            now += v,S.erase({pos,v});
            auto itr = S.lower_bound({pos,v});
            if(itr == S.end() || itr == S.begin()){
                if(S.size() == 0) break;
                if(itr == S.end()) itr--;
                S.erase(itr); break;
            }
            auto [ign,v3] = *itr; itr--;
            auto [IGN,v2] = *itr;
            S.erase({ign,v3}),S.erase({IGN,v2});
            S.insert({pos,v2+v3-v}),Q.push({v2+v3-v,pos});
            break;
        }  
    }
    cout << now << "\n";
}