#include <bits/stdc++.h>
using namespace std;
const long long INF = 1000000007;
const long long SZ = 3e5 + 1;
long long p;
long long fpow(long long a, long long k) {
  if (k == 0) return 1;
  if (k % 2 == 1)
    return (fpow(a, k - 1) * (long long)a) % p;
  else
    return fpow(((long long)a * a) % p, k / 2);
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  long long a, b, x, ans = 0;
  cin >> a >> b >> p >> x;
  for (long long i = 0; i < min(p - 1, x + 1); i++) {
    long long v = fpow(a, i);
    long long m = b * fpow(v, p - 2) % p;
    long long u = (i + p - m) % p;
    long long vl = ((x - i) / (p - 1) - u);
    if (vl < 0) continue;
    ans += vl / p + 1;
  }
  cout << ans;
  return 0;
}
