#include <iostream>
#include <vector>
using namespace std;

bool seenIT(unsigned long long sCurrent, vector<unsigned long long>& seen) {
    size_t blk = sCurrent >> 6;
    unsigned long long slot = 1ULL << (sCurrent & 63);
    if (seen[blk] & slot) return true;
    seen[blk] |= slot;
    return false;
}

int main() {
    unsigned long long n, s, p, q;
    cin >> n >> s >> p >> q;

    const unsigned long long RANGE = 1U << 31;            //this many different #s
    size_t blocks = (RANGE + 63) / 64;
    vector<unsigned long long> seen(blocks, 0);         //All start as 0, unseen
    seenIT(s, seen);
    
    bool earlyOut = false;
    for (int i = 1; i < n; i++) {
        s = (s * p + q) % RANGE;
        if (seenIT(s, seen)) {
            earlyOut = true;
            cout << i;
            break;
        }
    }
    if (!earlyOut)
        cout << n;

    return 0;
}