LCA gay shit

#include <bits/stdc++.h>

using namespace std;

#define endl "\n"

const int MAXN = 1e5 + 10, MAXM = 1e7 + 10;
int d[4 * MAXN];
vector <pair<int, int> > rmq;
vector <int> g[MAXN];
int founded[MAXN];
long long a[2 * MAXM];
bool used[MAXN];
long long n, m;

void full() {
    for (int i = 2; i < 4 * MAXN; i++)
        d[i] = d[i / 2] + 1;
}

void dfs(int u, int h, long long& i) {
    used[u] = true;
    founded[u] = i;
    rmq.push_back({h, u});
    for (int v : g[u]) {
        if (!used[v]) {
            i++;
            dfs(v, h + 1, i);
            rmq.push_back({h, u});
            i++;
        }
    }
}

/*
void print() {
    cout << " a " << endl;
    for (int i = 0; i < 2 * m; i++) {
        cout << a[i] << " ";
    }
    cout << endl << " rmq " << endl;
    for (unsigned i = 0; i < rmq.size(); i++) {
        cout << rmq[i].first << " ";
    }
    cout << endl;
    for (unsigned i = 0; i < rmq.size(); i++) {
        cout << rmq[i].second << " ";
    }
    cout << endl << " first meat " << endl;
    for (unsigned i = 0; i < n; i++) {
        cout << founded[i] << " ";
    }
    cout << endl << " Now program " << endl;
}
*/

signed main() {
/*
14 10
0 1 0 0 2 3 6 4 4 5 5 8 3
12 9
1 1 1
*/
    full();
    cin >> n >> m;
    for (int i = 1; i < n; i++) {
        int v;
        cin >> v;
        g[v].push_back(i);
        g[i].push_back(v);
    }
    cin >> a[0] >> a[1];
    long long x, y, z;
    cin >> x >> y >> z;
    for (int i = 2; i < 2 * m; i++) {
        a[i] = (x * a[i - 2] + y * a[i - 1] + z) % n;
    }
    long long o = 0;
    dfs(0, 0, o);
    //   print();
    pair<int, int> Sparse[rmq.size()][30];
    for (int i = 0; i < rmq.size(); i++) {
        Sparse[i][0] = rmq[i];
    }
    for (int k = 1; k < 20; k++) {
        for (int i = 0; i < (int) rmq.size() - (1 << (k - 1)); i++) {
            Sparse[i][k] = min(Sparse[i][k - 1], Sparse[i + (1 << (k - 1))][k - 1]);
        }
    }
    long long last_ans = 0, a1 = a[0], a2 = a[1];
    long long sum = 0;
    for (int i = 0; i < m; i++) {
        a1 = a[2 * i], a2 = a[2 * i + 1];
        a1 = (a1 + last_ans) % n;
        //   cout << a1 << " " << a2;
        int L = founded[a1], R = founded[a2];
        if (L > R) {
            swap(L, R);
        }
        //  cout << " [] " << L << " " << R << " " << d[R - L];
        pair <int, int> ans;
        if (R == L) {
            ans = Sparse[L][0];
        } else {
            int p = d[R - L];
            ans = min(Sparse[L][p], Sparse[R - (1 << (p))][p]);
        }
          //  cout << " LCA " << ans.second << endl;
          sum += ans.second;
          last_ans = ans.second;
    }
    cout << sum;
}