#include <bits/stdc++.h>

using namespace std;

int n;

vector<unsigned int> p;
vector<vector<unsigned int>> t;

void build(int v = 1, int tl = 0, int tr = n - 1) {
    if (tl == tr) {
        t[v].push_back(p[tl]);
        return;
    }

    int tm = (tl + tr) / 2;

    build(v * 2, tl, tm);
    build(v * 2 + 1, tm + 1, tr);

    merge(t[v * 2].begin(), t[v * 2].end(),
          t[v * 2 + 1].begin(), t[v * 2 + 1].end(),
          back_inserter(t[v]));
}

long long get(int l, int r, int x, int v = 1, int tl = 0, int tr = n - 1) {
    if (l > r) {
        return 0;
    }
    if (l == tl && r == tr) {
        return tr - tl + 1 -
        (upper_bound(t[v].begin(), t[v].end(), x) - t[v].begin());
    }

    int tm = (tl + tr) / 2;

    return get(l, min(r, tm), x, v * 2, tl, tm) +
            get(max(l, tm + 1), r, x, v * 2 + 1, tm + 1, tr);
}

unsigned int cur = 0, a, b;

unsigned int nextRand24() {
    cur = cur * a + b;
    return cur >> 8;
}

int main() {
    unsigned int m;
    cin >> n >> m;
    cin >> a >> b;

    p.resize(n);
    t.resize(4 * n);

    for (int i = 0; i < n; ++i) {
        p[i] = nextRand24() % m;
    }

    build();

    long long ans = 0;
    for (int i = 1; i < n; ++i) {
        ans += get(0, i - 1, p[i]);
    }
    cout << ans;
}