#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

#define rep(v,e) for(unsigned long v=0;v<e;++v)

#define MD 1000000007

int inverse(int a){
	int b=MD;
	int u=1;
	int v=0;
	while(b){
		int q=a/b,t;
		t=b, b=a-q*b, a=t;
		t=v, v=u-q*v, u=t;
	}
	if(u<0){
		u+=MD;
	}
	return u;
}

int main(){
	unsigned long n,k,a=1,b=0,c=1,d=1;
	scanf("%lu%lu",&n,&k);
	rep(i,n){
		b+=a;
		a=a*(k-1-i)%MD*(n-1-i)%MD;
		c=c*(k+i)%MD;
		unsigned long e=(k+n-1-i)*(1+i)%MD;
		b=b*e%MD;
		d=d*e%MD*(1+i)%MD;
	}
	printf("%lu\n",b%MD*c%MD*inverse(d)%MD);
	return 0;
}