//C(n+m-2,m-1)

#include<cstdio>

#include<cstring>

#include<cctype>

#include<algorithm>

using namespace std;

#define rep(i,s,t) for(int i=s;i<=t;i++)

#define dwn(i,s,t) for(int i=s;i>=t;i--)

#define ll long long

int read(){

	int x=0;char c=getchar();

	while(!isdigit(c)) c=getchar();

	while(isdigit(c)) x=x*10+c-'0',c=getchar();

	return x;

}

const int nmax=2e6+5;

const ll mod=1e9+7;

ll a[nmax];

ll pow(ll x,int n){

	ll ans=x;--n;

	while(n){

		if(n&1) ans=(ans*x)%mod;

		x=(x*x)%mod;n>>=1;

	}

	return ans;

}

int main(){

	int n=read(),m=read();a[0]=1;

	rep(i,1,n+m-2) a[i]=a[i-1]*i%mod;

	printf("%lld\n",a[n+m-2]*pow(a[n-1],mod-2)%mod*pow(a[m-1],mod-2)%mod);

	return 0;

}