#include <iostream>
#include <algorithm>
#include <vector>
#include <cstdio>

using namespace std;

const int N = 200010, MOD = 1000000007;

int n, b, ans, a[N];
bool st[N];

int QMI(int a, int k) {
    int ret = 1 % MOD;
    while (k) {
        if (k & 1) {
            ret = 1LL * ret * a % MOD;
        }
        a = 1LL * a * a % MOD;
        k >>= 1;
    }
   return ret;
}

void DFS(int rem, int ma, int cnt, int pre) {
    if (rem == 0) {
        // cout << "rem: " << rem << " ma: " << ma << " cnt: " << cnt << " pre: " << pre << "   " << 1LL * cnt * QMI(b, cnt) % MOD << endl;
        ans = (0LL + ans + 1LL * cnt * QMI(b, cnt) % MOD) % MOD;
        return;
    }
    for (int i = 1; i <= n; ++i) {
        if (!st[i]) {
            st[i] = true;
            if (a[i] > pre) ++cnt;
            DFS(rem - 1, max(ma, a[i]), cnt, max(pre, a[i]));
            if (a[i] > pre) --cnt;
            st[i] = false;
        }
    }
}

int main() {
    // freopen("growth.in", "r", stdin);
    // freopen("growth.out", "w", stdout);

    scanf("%d%d", &n, &b);
    for (int i = 1; i <= n; ++i) {
        scanf("%d", &a[i]);
    }

    DFS(n, 0, 0, -1);

    printf("%d\n", ans);

    return 0;
}