#include <cstdio>

using namespace std;

#define NMAX 100000
#define P 1000000007

bool ty[NMAX];

int main(){
	int n;
	int tt;
	long long sumb=0,sumw=0,ans=0;
	long long numb;
	int i,j;

	freopen("asm_code.in","r",stdin);
	freopen("asm_code.out","w",stdout);

	scanf("%d",&n);
	for(i=0;i<n;i++){
		scanf("%d",&tt);
		if(tt==1){
			ty[i]=true;
			sumb++;
		}else sumw++;
	}

	for(i=0;i<n;i++){
		numb=0;
		if(!ty[i])for(j=i+1;j<n;j++)
			if(ty[j])numb++;
			else ans=(ans+((sumb-numb)*numb)%P)%P;
	}
	printf("%lld",ans);
	return 0;
}