#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=4e5+10,M=20,INF=0x3f3f3f3f,mod=998244353;
int n,k,a[N],nxt[M][N];
namespace Fast_IO
{
	static char buf[1000000],*paa=buf,*pd=buf,out[10000000];int length=0;
	#define getchar() paa==pd&&(pd=(paa=buf)+fread(buf,1,1000000,stdin),paa==pd)?EOF:*paa++
	inline int read()
	{
		int x(0),t(1);char fc(getchar());
		while(!isdigit(fc)){if(fc=='-') t=-1;fc=getchar();}
		while(isdigit(fc)) x=(x<<1)+(x<<3)+(fc^48),fc=getchar();
		return x*t;
	}
	inline void flush(){fwrite(out,1,length,stdout);length=0;}
	inline void put(char c){if(length==9999999) flush();out[length++]=c;}
	inline void put(string s){for(char c:s) put(c);}
	inline void print(int x)
	{
		if(x<0) put('-'),x=-x;
		if(x>9) print(x/10);
		put(x%10+'0');
	}
	inline bool chk(char c) { return !(c>='a'&&c<='z'||c>='A'&&c<='Z'||c>='0'&&c<='9'||c=='.'||c=='#'); }
	inline bool ck(char c) { return c!='\n'&&c!='\r'&&c!=-1&&c!=' '; }
	inline void rd(char s[],int&n)
	{
		s[++n]=getchar();
		while(chk(s[n])) s[n]=getchar();
		while(ck(s[n])) s[++n]=getchar();
		n--;
	}
}
using namespace Fast_IO;
inline bool check(int x)
{
	for(int i=0;i<=2*n;i++) nxt[0][i]=lower_bound(a+1,a+1+(2*n),a[i]+x)-a;
	for(int k=0;k<M;k++) nxt[k][2*n+1]=2*n+1;
	for(int k=0;k+1<M;k++)
		for(int i=0;i<=2*n;i++)
			nxt[k+1][i]=nxt[k][nxt[k][i]];
	for(int i=1,j;i<=n;i++)
	{
		nxt[0][2*n]=2*n+1;j=i;
		for(int l=0;l<M;l++) if((k>>l)&1) j=nxt[l][j];
		if(j-i<=n) return true;
	}return false;
}
inline void solve()
{
	n=read(),k=read();for(int i=1;i<=n;i++) a[i+n]=a[i]=read();
	for(int i=1;i<=n<<1;i++) a[i]+=a[i-1];int l=0,r=INF,ans=0;
	while(l<=r)
	{
		int mid=(l+r)>>1;
		if(check(mid)) ans=mid,l=mid+1;
		else r=mid-1;
	}print(ans);
}
signed main()
{
	int T=1;while(T--) solve();
	genshin:;flush();return 0;
}