#include <iostream>
#include <set>
#include <vector>

using namespace std;
typedef long long int64;

int main() {
    int n, k; cin >> n >> k;
    int mod = 1e9 + 7;
    vector<set<int> > ve(n);
    for (int i = 0; i < n; ++i) {
        int to; cin >> to; --to;
        if (to == i) continue;
        if (to > i) ve[to].insert(i);
        if (to < i) ve[i].insert(to);
    }
    long long ans = 1;
    for (int i = 0; i < n; ++i) {
        ans = (ans * (k - ve[i].size())) % mod;
    }
    cout << ans << endl;
    return 0;
}