#include<bits/stdc++.h>
using namespace std;
#define IOS std::ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
#define int long long
#define ull unsigned long long
#define fi first
#define se second
#define lowbit(x) ((x)&(-x))
// #define pi pair<int,int>

const int N=1e6+10;
const int INF=1e18;
const int mod=1e9+7;

int b[N];

int quickpow(int a,int b){
    int ans=1;
    a%=mod;
    while(b){
        if(b&1) ans=ans*a%mod;
        b>>=1;
        a=a*a%mod;
    }
    return ans;
}

void solve(){
    int n,m;
    cin>>n>>m;
    int sum1=0,sum2=0;
    __int128 z=0,f=0;
    for(int i=1;i<=n;i++){
        cin>>b[i];
        sum1+=b[i];
        z+=sum1;
    }
    for(int i=n;i>=1;i--){
        sum2+=b[i];
        f+=sum2;
    }
    if(z<f){
        int now=z;
        int ss=sum1;
        int pre=n;
        ss%=mod;
        pre%=mod;
        now%=mod;
        for(int i=1;i<=m-1;i++){
            now=now+now+(pre*ss)%mod;
            now%=mod;
            // cout<<i<<" "<<now<<"\n";
            pre*=2;
            pre%=mod;
            ss*=2;
            ss%=mod;
        }
        // cout<<now<<"\n"; 
        int dnow=f;
        int dss=sum1;
        int dpre=n;
        dss%=mod;
        dpre%=mod;
        dnow%=mod;
        for(int i=1;i<=m-1;i++){
            dnow=dnow+dnow+(dpre*dss)%mod;
            dnow%=mod;
            dpre*=2;
            dpre%=mod;
            dss*=2;
            dss%=mod;
        }
        // cout<<dnow<<"\n"; 
        now=dnow+ss*dpre%mod+now;
        now%=mod;
        cout<<now<<"\n";
    }
    else{
        int now=z;
        int ss=sum1;
        int pre=n;
        ss%=mod;
        pre%=mod;
        now%=mod;
        for(int i=1;i<=m;i++){
            now=now+now+(pre*ss)%mod;
            now%=mod;
            // cout<<i<<" "<<now<<"\n";
            pre*=2;
            pre%=mod;
            ss*=2;
            ss%=mod;
        }
        cout<<now<<"\n";
    }
}   

signed main(){
    int _=1;
    // cin>>_;
    while(_--){
        solve();
    }
}