#include<bits/stdc++.h>
#pragma GCC optimize("O2")
#define F first
#define S second
#define PB push_back
#define MP make_pair
#define all(c) c.begin(), c.end()
#define endl "\n"
#define sz(u) (int)(u.size())
#define L(x)(2*x)
#define R(x)(2*x+1)
#define M(x,y)((x+y)/2)
typedef long long ll;
typedef unsigned long long ull;
using namespace std;
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n,k;
cin>>n>>k;
int t[n+1],diff[n+1];
for(int i=1;i<=n;i++)
cin>>t[i];
for(int i=2;i<=n;i++)
diff[i]=t[i]-t[i-1];
sort(diff+2,diff+n+1);
int cnt=0;
for(int i=2;i<=n;i++){
if(i>n-k+1)
cnt+=1;
else
cnt+=diff[i];
}
cout<<cnt+1;
}
