#include <bits/stdc++.h>
using namespace std;
int pow_mod(int a, int n, int m) {
  if (n == 0) return 1;
  int x = pow_mod(a, n / 2, m);
  long long ans = (long long)x * x % m;
  if (n % 2 == 1) ans = ans * a % m;
  return (int)ans;
}
int a, b, p;
long long x, ans;
int main() {
  cin >> a >> b >> p >> x;
  for (int j = 0; j < p - 1; ++j) {
    long long tmp = (1LL * pow_mod(a, p - 1 - j, p) * b - j + p) % p;
    if (tmp) tmp = p - tmp;
    if (tmp * (p - 1) + j <= x) ans += ((x - j) / (p - 1) - tmp) / p + 1;
  }
  cout << ans << endl;
  return 0;
}
