#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N=3,M=1e6,mod=1000000007;
int n;
int a[N],inv[M],f[M];
int ksm(int a,int b){
    int res=1;
    for(;b;b>>=1,a=(1ll*a*a)%mod){
        if(b&1) res=(res*a)%mod;
    }
    return res;
}
void init(){
    inv[0]=inv[1]=1ll;
    f[1]=1ll;
    for(int i=2;i<M;++i){
        f[i]=(f[i-1]*i)%mod;
        inv[i]=ksm(f[i],mod-2);
    }
}
int C(int y,int x){
    return (f[x]*inv[y]%mod*inv[x-y])%mod;
}
signed main(){
	freopen("moorouteg.in","r",stdin);
	freopen("moorouteg.out","w",stdout);
	init();
	scanf("%lld",&n);
	for(int i=1;i<=n;i++){
		scanf("%lld",&a[i]);
		a[i]/=2;
	}
	if(a[1]<=a[2]){
		cout<<C(a[1]-1,a[2]-1)<<endl;
	}else{
		cout<<C(a[2],a[1])<<endl;
	}
	return 0;
}