#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long ull;
 
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n; cin >> n;
    ll k; cin >> k;
    vector<ll> a(n);
    ll mod=0;
    for(int i=0;i<n;i++){
        cin >> a[i];
        mod+=a[i];
    }
    ll res=0;
    ll base=1;
    for(int i=n-1;i>=0;i--){
        (res+=base*a[i])%=mod;
        base=(base*k)%mod;
    }
    cout << res << endl;
}