#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N=1000009;
ll n,k;
ll s[N];
struct Info{
	ll id,gcd;
};
Info f[2][N];
ll sz[2];
ll x[N];
ll GCD(ll a,ll b){
	return a%b?GCD(b,a%b):b;
}
int main(){
	freopen("skyline.in","r",stdin);
	freopen("skyline.out","w",stdout);
	scanf("%d%d",&n,&k);
	for(int i=1;i<=n;++i)scanf("%d",&x[i]);
	for(int i=1;i<=n;++i)s[i]=s[i-1]+x[i];
	ll ans=0;
	ll now=0;
	for(int r=1;r<=n;++r){
		for(int j=1;j<=sz[now];++j)
			f[now][j].gcd=GCD(f[now][j].gcd,x[r]);
		f[now][++sz[now]]=(Info){r,x[r]};
		ll nxt=1-now;
		sz[nxt]=1;
		f[nxt][1]=f[now][1];		
		for(int j=2;j<=sz[now];++j)
			if(f[now][j].gcd!=f[now][j-1].gcd)
				f[nxt][++sz[nxt]]=f[now][j];		
		for(int j=1;j<=sz[nxt];++j){
			ll l=f[nxt][j].id;
			if(r-l+1<k) break;
			ans=max(ans,f[nxt][j].gcd*(s[r]-s[l-1]));
		}
		now=nxt;
	}
	printf("%lld\n",ans);
	return 0;
}