#include <bits/stdc++.h> #define FOR(i,a,b) for(int i = a; i<=b; i++) #define FORD(i,a,b) for(int i = a; i>=b; i--) #define vi vector<int> #define vll vector<long long> #define pb push_back /* Author: DreamNguyen aka Nguyen Minh Triet */ using namespace std; using ll = long long; const int maxN = 1e5; int n, k; ll t[maxN+5], que[maxN+5]; void nhap() { cin>>n>>k; FOR(i,1,n) cin>>t[i]; } void giai() { if(n==k) return void(cout<<n); ll ans = t[n]-t[0]+1; FOR(i,1,n-1) que[i] = t[i+1]-t[i]-1; sort(que+1,que+1+n); FORD(i,n,n-k+1) ans -= que[i]; cout<<ans; } int main() { ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); nhap(); giai(); return 0; }