#include <iostream>
using namespace std;
typedef long long ll;
const int M=int(1e9)+7;
ll pow(ll a,ll b){
if(b==0) return 1;
ll ret=pow(a,b/2);
ret=(ret*ret)%M;
if(b&1) ret=(ret*a)%M;
return ret;
}
int main()
{
ll p,q,n,k;
cin>>p>>q>>n>>k;
if(k==0){ cout<<0; return 0; }
if(k==n){ cout<<1; return 0; }
if(q==0){
cout<<1;
return 0;
} else if(p==q){
cout<<0;
return 0;
} else if(p == 2*q){
cout<<(k*pow(n,M-2))%M;
return 0;
}
int rja=q, rmo=p-q;
ll r=rja*pow(rmo,M-2)%M;
ll bunja = (M + 1 - pow(r,k))%M;
ll bunmo = (M + 1 - pow(r,n))%M;
cout<<(bunja*pow(bunmo,M-2)%M);
return 0;
}
