#include<bits/stdc++.h>
#include<atcoder/math.hpp>
using namespace std;
using ll=long long;
#define rep(i,n) for(int i=0;i<(n);++i)

vector<vector<long long>> make_mat(vector<long long> v){
    if(v.empty())return vector<vector<long long>>(1,vector<long long>());
    long long n=v.back();
    v.pop_back();
    vector<vector<long long>> ret;
    vector<vector<long long>> tmp=make_mat(v);
    for(auto e:tmp)for(long long i=0;i<n;++i){
        ret.push_back(e);
        ret.back().push_back(i);
    }
    return ret;
}

ll euler_phi(ll n) {
  ll ret = n;
  for(ll i = 2; i * i <= n; i++) {
    if(n % i == 0) {
      ret -= ret / i;
      while(n % i == 0) n /= i;
    }
  }
  if(n > 1) ret -= ret / n;
  return ret;
}

int main(){
    ll m,d,n,b;
    cin>>m>>d>>n>>b;
    vector<ll>phi=vector{b};
    while(phi.back()!=1){
        phi.emplace_back(euler_phi(phi.back()));
    }
    auto mul=[&](vector<ll>v){
        vector<ll>res(phi.size());
        rep(i,phi.size()-1){
            ll tmp=1;
            bool over=0;
            rep(j,v[i+1]){
                tmp*=v[i]+d;
                if(tmp>=phi[i]*2)tmp=tmp%phi[i]+phi[i];
            }
            res[i]=tmp;
        }
        return res;
    };
    auto tb=phi;
    rep(i,phi.size())tb[i]*=2;
    map<vector<ll>,vector<ll>>ma;
    for(auto v:make_mat(tb)){
        ma[v]=mul(v);
    }
    vector<ll>v(phi.size());
    rep(i,phi.size())v[i]=m%phi[i]+(m>=phi[i]?phi[i]:0);
    auto ans=v;
    // cerr<<n<<endl;
    // rep(i,phi.size())cerr<<phi[i]<<ans[i]<<" \n"[i==phi.size()-1];
    while(n){
        if(n%2){
            ans=ma[ans];
            // rep(i,phi.size())cerr<<phi[i]<<ans[i]<<" \n"[i==phi.size()-1];
        }
        map<vector<ll>,vector<ll>>ma2;
        for(auto [s,t]:ma){
            ma2[s]=mul(t);
        }
        n/=2;
        swap(ma,ma2);
    }
    if(ans[0]%b==10)cout<<"A"<<endl;
    else cout<<ans[0]%b<<endl;
}