#include <iostream>
#include <string>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <iterator>
#include <cassert>
#include <numeric>
#include <functional>
#include <ctime>
#pragma warning(disable:4996) 

//#define ATCODER
#ifdef ATCODER
#include <atcoder/all>
#endif

typedef long long ll;
typedef unsigned long long ull;
#define LINF  9223300000000000000
#define LINF2 1223300000000000000
#define LINF3 1000000000000
#define INF 2140000000
//const long long MOD = 1000000007;
const long long MOD = 998244353;

using namespace std;
#ifdef ATCODER
using namespace atcoder;
#endif


void solve()
{
    int n, K;
    scanf("%d%d", &n, &K);
    vector<ll> a(n);
    int i;
    ll s = 0;
    for (i = 0; i < n; i++) {
        scanf("%lld", &a[i]);
        s += a[i];
    }
    ll ans = 0;
    for (i = 0; i < n; i++) {
        ans = (ans*K + a[i]) % s;
    }
    printf("%lld\n", ans);

    return;
}

int main()
{
#if 1
    solve();
#else
    int T, t;
    cin >> T;
    for (t = 0; t < T; t++) {
        //cout << "Case #" << t + 1 << ": ";
        solve();
    }
#endif
    return 0;
}