#include <bits/stdc++.h>
using namespace std;
#define taskname "JOI18_stove"
#define forinc(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define fordec(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
#define foreach(i, x) for (auto &i : x)
#define ms(x, n) memset(x, n, sizeof(x))
#define sz(x) int((x).size())
#define all(x) (x).begin(), (x).end()
#define uni(x) (x).erase(unique(all(x)), (x).end())
#define fi first
#define se second
#define pb push_back
#define pf push_front
template<typename TH>
void _dbg(const char* sdbg, TH h)
{
cerr << sdbg << " = " << h << "\n";
}
template<typename TH, typename... TA>
void _dbg(const char* sdbg, TH h, TA... t)
{
while (*sdbg != ',') cerr << *sdbg++;
cerr << " = " << h << ",";
_dbg(sdbg + 1, t...);
}
#define db(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#define chkpt cerr << "--- Checkpoint here ---\n";
const int N=1e5+5;
const int64_t LINF=1e18;
int n,k;
int64_t a[N],f[5005][5005],g[5005][5005];
void Sub2()
{
forinc(i,0,n)
{
forinc(j,0,k)
{
f[i][j]=LINF;
g[i][j]=LINF;
}
}
f[0][0]=0;
// g[i][j] = min(f[0<=x<=i][j]-a[x+1])
forinc(i,0,n)
{
g[i][0]=-a[1];
}
forinc(i,1,n)
{
forinc(j,1,k)
{
// forinc(p,0,i-1)
// {
// if(f[p][j-1]!=LINF)
// {
// f[i][j]=min(f[i][j],f[p][j-1]+(a[i]-a[p+1]+1));
// }
// }
if(g[i-1][j-1]!=LINF)
{
f[i][j]=g[i-1][j-1]+a[i]+1;
g[i][j]=min(g[i-1][j],f[i][j]-a[i+1]);
}
}
}
int64_t ans=LINF;
forinc(i,0,k)
{
ans=min(ans,f[n][i]);
}
cout<<ans<<'\n';
}
void Sub3()
{
vector<int> vec;
forinc(i,1,n-1)
{
vec.pb(a[i]-a[i+1]);
}
sort(all(vec));
int ans=k-a[1]+a[n];
forinc(i,0,k-2)
{
ans+=vec[i];
}
cout<<ans;
}
int64_t Random(int64_t l,int64_t r)
{
int64_t f1=RAND_MAX+1;
int64_t f2=f1*f1;
int64_t f3=f1*f1*f1;
return l+((int64_t)rand()*f3+(int64_t)rand()*f2+(int64_t)rand()*f1+(int64_t)rand())%(r-l+1);
}
void Gen()
{
srand(time(0));
freopen("JOI18_stove.INP","w",stdout);
int n=Random(1,10);
int k=Random(1,n);
cout<<n<<' '<<k<<'\n';
int x=Random(1,10);
cout<<x<<' ';
forinc(i,2,n)
{
int64_t y=x+1+Random(1,1e5);
cout<<y<<' ';
x=y;
}
exit(0);
}
int main()
{
// Gen();
ios_base::sync_with_stdio(0);
cin.tie(0);
#ifndef ONLINE_JUDGE
// freopen(taskname".INP","r",stdin);
#endif // ONLINE_JUDGE
cin>>n>>k;
forinc(i,1,n)
{
cin>>a[i];
}
if(n<=5e3)
{
Sub2();
}
else
{
Sub3();
}
return 0;
}
