#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
constexpr int M=3e5+5;
int n,k,a[M<<1],b[M<<1],q[M];
ll ans=1ll<<60,f[M],g[M],stk[M];
int read(){
    int x=0;char ch=getchar();
    while (!isdigit(ch)) ch=getchar();
    while (isdigit(ch)) x=x*10+ch-48,ch=getchar();
    return x;
}
double slope(int x,int y){return (double)(f[x]-f[y])/(double)(b[x]-b[y]);}
void subtask1(){
    for (int i=1;i<=n;i++) a[i+n]=a[i];
    for (int i=1;i<=n<<1;i++) b[i]=b[i-1]+a[i];
    int res=b[n]>>1;
    for (int i=1,j=1;i<=n;i++){
        while (b[j]-b[i-1]<res) j++;  int tmp=b[j]-b[i-1];
        ans=min(ans,1ll*tmp*tmp+1ll*(b[n]-tmp)*(b[n]-tmp));
    }
    printf("%lld\n",1ll*ans*k*k-1ll*b[n]*b[n]*k);
}
void subtask2(){
    for (int i=1;i<=n;i++) a[i+n]=a[i];
    for (int i=1;i<=n<<1;i++) b[i]=b[i-1]+a[i];
    int res=b[n]/3;
    for (int i=1,j=1,k=1;i<=n;i++){
        while (b[j]-b[i-1]<res) j++;
        int tmp1=b[j]-b[i-1],Res=b[n]-tmp1>>1;
        while (b[k]-b[j-1]<Res) k++;
        int tmp2=b[k]-b[j-1];
        ans=min(ans,1ll*tmp1*tmp1+1ll*tmp2*tmp2+1ll*(b[n]-tmp1-tmp2)*(b[n]-tmp1-tmp2));
    }
    printf("%lld\n",1ll*ans*k*k-1ll*b[n]*b[n]*k);
}
void calc(){
    for (int i=1;i<=n;i++) b[i]=b[i-1]+a[i];
    for (int i=1;i<=n;i++) f[i]=1ll<<60;
    for (int T=1;T<=k;T++){
        for (int i=1,head=0,tail=0;i<=n;i++){
            while (head<tail&&slope(q[head],q[head+1])<b[i]*2.) head++;
            g[i]=f[q[head]]-2ll*b[q[head]]*b[i];
            while (head<tail&&slope(q[tail-1],q[tail])>slope(q[tail],i)) tail--;
            q[++tail]=i;
        }
        for (int i=1;i<=n;i++) f[i]=g[i]+2ll*b[i]*b[i];
    }
    ans=min(ans,f[n]-1ll*b[n]*b[n]);
    int tmp=a[1];
    for (int i=1;i<n;i++) a[i]=a[i+1];
    a[n]=tmp;
}
int main(){
    n=read();k=read();
    for (int i=1;i<=n;i++) a[i]=read();
    if (k==2) return subtask1(),0;
    if (k==3) return subtask2(),0;
    for (int T=1;T<=n;T++) calc();
    printf("%lld\n",1ll*ans*k*k-1ll*b[n]*b[n]*k);
    return 0;
}