#include using namespace std; #define rep(i,n) for(ll i=0;i=0;i--) #define perl(i,r,l) for(ll i=r-1;i>=l;i--) #define fi first #define se second #define pb push_back #define ins insert #define pqueue(x) priority_queue,greater> #define all(x) (x).begin(),(x).end() #define CST(x) cout<> #define rev(x) reverse(x); using ll=long long; using vl=vector; using vvl=vector>; using pl=pair; using vpl=vector; using vvpl=vector; const ll MOD=1000000007; const ll MOD9=998244353; const int inf=1e9+10; const ll INF=4e18; const ll dy[9]={0,1,-1,0,1,1,-1,-1,0}; const ll dx[9]={1,0,0,-1,1,-1,1,-1,0}; template inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; } template inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; } const int mod = MOD9; const int max_n = 200005; struct mint { ll x; // typedef long long ll; mint(ll x=0):x((x%mod+mod)%mod){} mint operator-() const { return mint(-x);} mint& operator+=(const mint a) { if ((x += a.x) >= mod) x -= mod; return *this; } mint& operator-=(const mint a) { if ((x += mod-a.x) >= mod) x -= mod; return *this; } mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;} mint operator+(const mint a) const { return mint(*this) += a;} mint operator-(const mint a) const { return mint(*this) -= a;} mint operator*(const mint a) const { return mint(*this) *= a;} mint pow(ll t) const { if (!t) return 1; mint a = pow(t>>1); a *= a; if (t&1) a *= *this; return a; } bool operator==(const mint &p) const { return x == p.x; } bool operator!=(const mint &p) const { return x != p.x; } bool operator<(const mint &p) const { return x < p.x; } // for prime mod mint inv() const { return pow(mod-2);} mint& operator/=(const mint a) { return *this *= a.inv();} mint operator/(const mint a) const { return mint(*this) /= a;} }; istream& operator>>(istream& is, mint& a) { return is >> a.x;} ostream& operator<<(ostream& os, const mint& a) { return os << a.x;} using vm=vector; using vvm=vector; vvm matmul(vvm left,vvm right){ ll m=left.size(); vvm ret(m,vm(m,0)); rep(i,m)rep(j,m)rep(k,m){ ret[i][j]+=left[i][k]*right[k][j]; } return ret; } int main(){ mint a,b,p,q;cin >> a >> b >> p >> q; if(b==0){ ll m=100010; map mp; mint now=1; rep(i,m){ mp[now]=i; now*=a; } mint to=p; rep(i,m){ if(mp.count(to)){ if(i*m+mp[to]) cout << i*m+mp[to] < mp; vvm now(2,vm(2));now[0][0]=1,now[1][1]=1; vvm A(2,vm(2));A[0][0]=a,A[0][1]=-b,A[1][0]=1; rep(i,m){ vm x(2); x[0]=now[0][0]*2+now[0][1]*a/b; x[1]=now[1][0]*2+now[1][1]*a/b; mp[x]=i; now=matmul(A,now); } vvm iA=A;swap(iA[0][0],iA[1][1]);iA[1][0]*=-1,iA[0][1]*=-1; mint det=A[0][0]*A[1][1]-A[0][1]*A[1][0]; rep(i,2)rep(j,2)iA[i][j]/=det; vm to={p,q}; rep(i,m){ if(mp.count(to)){ cout << i*m+mp[to] <