/*=====================================
*   
*   AUTHOR : maxkibble
*   CREATED: 2019.09.08 15:39:59
*   PROBELM: UVALive 3722
*
=====================================*/


#include <bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define pb push_back

typedef long long ll;
typedef pair<int, int> pii;

ll mypow(ll a, ll n, ll c) {
  ll ans = 1;
  while (n) {
    if (n & 1) ans = ans * a % c;
    a = a * a % c;
    n >>= 1;
  }
  return ans;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0); cout.tie(0);
  ll x, a, n, c;
  while (cin >> x >> a >> n >> c) {
    if (x == 0) break;
    ll an = mypow(a, n, c);
    ll A = an * x % c;
    ll B = ((an - 1) % c + c) % c * a % c;
    ll C = mypow(a - 1, c - 2, c);
    ll ans;
    if ((a - 1) % c == 0) {
      assert(A == x % c);
      ans = A - n % c;
    }
    else ans = A - B * C;
    ans = (ans % c + c) % c;
    cout << ans << "\n";
  }
  return 0;
}