#include using namespace std; #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define REP(i,n) FOR(i,0,n) #define ALL(v) begin(v),end(v) template inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; } template inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; } using ll = long long; using pii = pair; constexpr ll INF = 1ll<<30; constexpr ll longINF = 1ll<<60; constexpr ll MOD = 1000000007; constexpr bool debug = false; //---------------------------------// int main() { int N, K; cin >> N >> K; vector A(N); REP(i, N) scanf("%lld", &A[i]); sort(ALL(A)); priority_queue pq; FOR(i, 1, N) pq.emplace(A[i] - A[i - 1]); ll ans = A[N - 1] - A[0]; REP(i, K - 1) { ans -= pq.top(); pq.pop(); } cout << ans << endl; }