#include<iostream>
using namespace std;
const long mod=1e9+7;
long N,K,A,B;
long power(long a,long b){return b?power(a*a%mod,b/2)*(b%2?a:1)%mod:1;}
long fac[2<<17],inv[2<<17];
main()
{
	cin>>A>>B>>N>>K;
	A%=mod;
	B%=mod;
	fac[0]=1;
	for(int i=1;i<=N;i++)fac[i]=fac[i-1]*i%mod;
	inv[N]=power(fac[N],mod-2);
	for(int i=N;i--;)inv[i]=inv[i+1]*(i+1)%mod;
	cout<<(A*fac[N-1]%mod*inv[K-1]%mod*inv[N-K]%mod+B*fac[N-1]%mod*inv[K-2]%mod*inv[N-K+1]%mod)%mod<<endl;
	long ans=0;
	for(int k=1;k<=N+1;k++)
	{
		long T=A*fac[N-1]%mod*inv[k-1]%mod*inv[N-k]%mod+B*fac[N-1]%mod*inv[k-2]%mod*inv[N-k+1]%mod;
		T%=mod;
		ans+=T*T%mod;
	}
	cout<<ans%mod<<endl;
}