#include <bits/stdc++.h> using namespace std; #include <atcoder/all> using namespace atcoder; using mint = atcoder::static_modint<998244353>; // using mint = atcoder::static_modint<1000000007>; using ld = long double; using ll = long long; #define mp(a,b) make_pair(a,b) #define rep(i,s,n) for(int i=s; i<(int)n; i++) const vector<int> dx{1,0,-1,0},dy{0,1,0,-1}; int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); int n,k;cin >> n >> k; vector<ll> a(n);rep(i,0,n)cin >> a[i]; while(a.size()>k && a.back()<=0)a.pop_back(); n=a.size(); priority_queue<ll> Q; ll s=0; Q.push(0); for(int i=n-1; i>=1; i--){ s+=a[i]; Q.push(s); } ll ans=accumulate(a.begin(),a.end(),0LL); rep(i,0,k-1)ans+=Q.top(),Q.pop(); cout<< ans; }