Jewel eating Monster

//This code is wrong! Sorry :'(

#include <bits/stdc++.h>
using namespace std;
#define F(W) for(int i(0);i<W;++i)
#define FF(W) for(int j(0);j<W;++j)
#define FT(I,W) for(int k(I);k<W;++k)
#define ZERO (1e-10)
#define EPS ZERO
#define INF (1<<30)
#define LINF (1LL<<60)
#define NINF (-(1<<30))
#define MP(A,B) make_pair(A,B)
#define CL(A,I) (memset(A,I,sizeof(A)))
#define ADD(A,B,V) (g[A].push_back(B),g[B].push_back(A),v[A].push_back(V),v[B].push_back(V))
#define add(A,B) (g[A].push_back(B),g[B].push_back(A))
#define DEB printf("DEB!\n");
#define DEX printf("DD2!\n");
#define EQ(A,B) (A+ZERO>B&&A-ZERO<B)
typedef long long ll;
typedef pair<ll, ll> pll;
typedef vector<int> vi;
typedef pair<int, int> ii;
#define REP(i, n) for (int i = 0; i < n; i++)
#define IN(n) int n; cin >> n;
#define PB push_back
ll X,A,N,C;
ll pw(ll n,ll k){
    ll r(1);
    while(k){
        if(k&1)
            r*=n,r%=C;
        n*=n,n%=C;
        k>>=1;
    }
    return r;
}
ll gcdE(ll a,ll m,ll &x,ll &y){
    if(!a)return x=0,y=1,m;
    ll u,v,g(gcdE(m%a,a,u,v));
    return x=v-(m/a)*u,y=u,g;
}
ll inv(ll a,ll m=C){
    ll x,y,g(gcdE(a,m,x,y));
    return g==1?(x%m+m)%m:-1;
}
#define MD(W) ((W)%C)
ll spec(ll N,ll X,ll A){
    return MD(MD(pw(A,N)*MD(A*(X-1)-X)+A)*inv(A-1));
}
int main(void){
    while(scanf("%lld%lld%lld%lld",&X,&A,&N,&C),X)
        printf("%lld\n",spec(N,X,A));
    return 0;
}