#include <bits/stdc++.h>

#define int long long
constexpr int MOD = 1e9 + 7;

int qpow(int a, int b) {
    int res = 1;
    while (b) {
        if (b & 1) res = res * a % MOD;
        a = a * a % MOD;
        b >>= 1;
    }
    return res;
}

int f[300005];

signed main() {
    int n, m;
    std::cin >> n >> m;
    int sum = 0;
    for (int i = 1; i <= n; i++) {
        int x;
        std::cin >> x;
        sum = (sum + x) % MOD;
    }
    f[2] = 4;
    for (int i = 3; i <= m; i++) {
        f[i] = (f[i - 1] * 2 % MOD + qpow(4, i - 1)) % MOD;
    }
    int ans = 0;
    int k = sum * n % MOD;
    for (int i = 1; i < m; i++) {
        int a = sum * qpow(2, i - 1) % MOD * ((n * qpow(2, i) % MOD + 1) % MOD) % MOD;
        int N = m - i + 1;
        int tmp = (qpow(2, N - 1) * a % MOD + k * f[N] % MOD) % MOD;
        ans = std::max(ans, tmp);
        k = k * 2 % MOD;
    }
    ans = std::max(ans, sum * qpow(2, m - 1) % MOD * ((n * qpow(2, m) % MOD + 1) % MOD) % MOD);
    std::cout << ans << '\n';
}