#line 1 "g.cpp"
#pragma region Macros
#include <bits/stdc++.h>
using namespace std;
template <class T> inline bool chmax(T &a, T b) {
    if(a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <class T> inline bool chmin(T &a, T b) {
    if(a > b) {
        a = b;
        return 1;
    }
    return 0;
}
#ifdef DEBUG
template <class T, class U>
ostream &operator<<(ostream &os, const pair<T, U> &p) {
    os << '(' << p.first << ',' << p.second << ')';
    return os;
}
template <class T> ostream &operator<<(ostream &os, const vector<T> &v) {
    os << '{';
    for(int i = 0; i < (int)v.size(); i++) {
        if(i) { os << ','; }
        os << v[i];
    }
    os << '}';
    return os;
}
void debugg() { cerr << endl; }
template <class T, class... Args>
void debugg(const T &x, const Args &... args) {
    cerr << " " << x;
    debugg(args...);
}
#define debug(...)                                                             \
    cerr << __LINE__ << " [" << #__VA_ARGS__ << "]: ", debugg(__VA_ARGS__)
#define dump(x) cerr << __LINE__ << " " << #x << " = " << (x) << endl
#else
#define debug(...) (void(0))
#define dump(x) (void(0))
#endif

struct Setup {
    Setup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(15);
    }
} __Setup;

using ll = long long;
#define ALL(v) (v).begin(), (v).end()
#define RALL(v) (v).rbegin(), (v).rend()
#define FOR(i, a, b) for(int i = (a); i < int(b); i++)
#define REP(i, n) FOR(i, 0, n)
const int INF = 1 << 30;
const ll LLINF = 1LL << 60;
constexpr int MOD = 998244353;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

void Case(int i) { cout << "Case #" << i << ": "; }
int popcount(int x) { return __builtin_popcount(x); }
ll popcount(ll x) { return __builtin_popcountll(x); }
#pragma endregion Macros

#line 1 "/home/siro53/kyo-pro/compro_library/math/pow_mod.hpp"
ll pow_mod(ll n, ll k, ll mod) {
    if(k == 0) {
        return 1;
    } else if(k % 2 == 1) {
        return pow_mod(n, k - 1, mod) * n % mod;
    } else {
        ll t = pow_mod(n, k / 2, mod);
        return t * t % mod;
    }
}
#line 1 "/home/siro53/kyo-pro/compro_library/math/BSGS.hpp"
// 与えられたx, y, pに対して、x^i=y(mod p)を満たす最小の正の整数iを返す
// 存在しない場合は-1
// O(√p log(p))
ll modlog(ll x, ll y, ll p) {
    ll H = sqrt(p) + 1;
    pair<ll, ll> baby[H];
    for(ll b = 0, xby = y; b < H; b++, xby = (xby * x) % p) {
        baby[b] = make_pair(xby, b);
    }
    sort(baby, baby + H);
    ll xH = 1;
    for(int i = 0; i < H; ++i) {
        xH = (xH * x) % p;
    }
    for(ll a = 1, xaH = xH; a <= H; a++, xaH = (xaH * xH) % p) {
        auto it = lower_bound(baby, baby + H, make_pair(xaH + 1, 0LL));
        if(it == baby) {
            continue;
        }
        it--;
        if(it->first == xaH) {
            return a * H - it->second;
        }
    }
    return -1;
}
#line 73 "g.cpp"

int main() {
    ll A, B, P, Q;
    ll y = (Q - (P * pow_mod(A, MOD-2, MOD) % MOD) + MOD) % MOD;
    ll res = modlog(B, y, MOD);
    assert(res != -1);
    res += 2;
    cout << res << endl;
}