#include using namespace std; const long mod=1e9+7; long power(long a,long b){return b?power(a*a%mod,b/2)*(b%2?a:1)%mod:1;} int N,K; long A[2<<17]; long S[2<<17]; //H(a,K)=C(a+K-1,K)=C(a+K-1,a-1) long H[2<<17]; main() { cin>>N>>K; for(int i=0;i>A[i]; S[i+1]=S[i]+A[i]; S[i+1]%=mod; } if(K==0) { cout<=1;i--) { (cum+=H[N-i+1])%=mod; (ans+=(mod-S[i-1])*cum%mod*H[i]%mod)%=mod; } cout<