#include<cstdio>
#include<algorithm>
using namespace std;
const int N=50010,M=N*18;
int n,m,K,i,a[N],tot,T[N],l[M],r[M],v[M],tmp,ans,s[N],g[M*2];double L,R,MID,f[M*2];
struct E{int l,r,v;E(){}E(int _l,int _r,int _v){l=_l,r=_r,v=_v;}}e[M*2];
inline bool cmp(const E&a,const E&b){return a.l<b.l;}
inline void read(int&a){char c;while(!(((c=getchar())>='0')&&(c<='9')));a=c-'0';while(((c=getchar())>='0')&&(c<='9'))(a*=10)+=c-'0';}
int ins(int x,int a,int b,int c,int p){int y=++tot;v[y]=p;if(a==b)return y;int mid=(a+b)>>1;if(c<=mid)l[y]=ins(l[x],a,mid,c,p),r[y]=r[x];else l[y]=l[x],r[y]=ins(r[x],mid+1,b,c,p);return y;
}
void ask(int x,int a,int b,int c,int d){if(!x)return;if(c<=a&&b<=d){if(v[x]>tmp)tmp=v[x];return;}int mid=(a+b)>>1;if(c<=mid)ask(l[x],a,mid,c,d);if(d>mid)ask(r[x],mid+1,b,c,d);
}
inline void findbigger(int x){int l=a[x]+1,r=n,t=x-1;while(l<=r&&t){tmp=0;ask(T[t],1,n,l,r);if(!tmp)return;t=tmp;e[++m]=E(t,x,a[t]-a[x]);r=(a[x]+a[t--]-1)>>1;}
}
inline void findsmaller(int x){int l=1,r=a[x]-1,t=x-1;while(l<=r&&t){tmp=0;ask(T[t],1,n,l,r);if(!tmp)return;t=tmp;e[++m]=E(t,x,a[x]-a[t]);l=(a[x]+a[t--]+2)>>1;}
}
inline void up(int&x,int y){if(f[x]>f[y])x=y;}
inline void cal(){int i,j;for(i=1;i<=n;i++)s[i]=0;for(i=1,j=ans=0;i<=m;i++){while(j+1<e[i].l){j++;up(s[j],s[j-1]);}f[i]=f[s[j]]+e[i].v+MID;g[i]=g[s[j]]+1;up(s[e[i].r],i);up(ans,i);}
}
int main(){read(n),read(K);for(i=1;i<=n;i++)read(a[i]),T[i]=ins(T[i-1],1,n,a[i],i);for(i=1;i<=n;i++)findbigger(i),findsmaller(i);sort(e+1,e+m+1,cmp);L=-1e9,R=1e9;for(int _=80;_;_--){MID=(L+R)/2;cal();if(g[ans]==K)break;if(g[ans]<K)R=MID;else L=MID;}return printf("%.0f",f[ans]-MID*K),0;
}