#include <bits/stdc++.h>
using namespace std;
const int maxn = 100005;
int n, k;
int a[maxn];
namespace sub1
{
long long dp[5005][5005];
long long opt[5005];
void solve()
{
memset(dp,0x3f,sizeof dp);
memset(opt,0x3f,sizeof opt);
dp[0][0] = opt[0] = 0;
for(int j=1;j<=k;j++)
{
for(int i=1;i<=n;i++)
{
opt[i] = min(opt[i-1], dp[i-1][j-1] - a[i]);
}
for(int i=1;i<=n;i++)
{
dp[i][j] = opt[i] + a[i]+1;
}
}
cout << dp[n][k];
}
}
namespace sub2
{
bool dd[maxn];
void solve()
{
vector<pair<int,pair<int,int>>> diff;
for(int i=2;i<=n;i++) diff.push_back({a[i] - a[i-1], {i-1,i}});
sort(diff.begin(),diff.end());
k--;
while(k--)
{
dd[diff.back().second.second] = 1;
diff.pop_back();
}
long long ans = 0;
for(int i=1;i<=n;i++)
{
int j = i + 1;
while(j <=n && !dd[j]) j++;
j--;
ans+= a[j]-a[i]+1;
i = j;
}
cout << ans;
}
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
// freopen("joi18_stove.inp", "r", stdin);
// freopen("joi18_stove.out", "w", stdout);
cin >> n >> k;
for(int i=1;i<=n;i++) cin>>a[i];
sort(a+1,a+1+n);
//return sub1::solve(),0;
return sub2::solve(),0;
return 0;
}
