ll n,k,a[1d5];
ll g,h,m;

ll j,s;
ll c[1d5],d[1d5],e[1d5];
bool f(ll m){
	j=s=0;
	rep(i,n){
		while(s<m){
			s+=a[j++%n];
			if(j-i>n){
				return false;
			}
		}
		c[i]=j;
		s-=a[i];
	}
	rrep(i,n){
		if(c[i]>=n){
			d[i]=1,e[i]=c[i]-n;
		}else{
			d[i]=1+d[c[i]],e[i]=e[c[i]];
		}
		if(d[i]==k && e[i]<=i){
			return true;
		}
	}
	return false;
}

{
	rd(n,k,a(n));
	g=1;
	h=1d14+1;
	while(g+1<h){
		m=g+h>>1;
		if(f(m)){
			g=m;
		}else{
			h=m;
		}
	}
	wt(g);
}