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

#define getrp() ({char*mmap();mmap(0l,1l<<25,1,2,0,0ll);})
#define rd_skip() while(*rp++>=48)
#define rd() ({int _v=0,_c;while(_c=*rp++-48,_c>=0)_v=_v*10+_c;_v;})
#define wt(v) ({unsigned _z=v;do*--wp=_z%10+48;while(_z/=10);})
#define wt1(v) ({char wbuf[64],*wp=wbuf+sizeof wbuf;wt(v);write(1,wp,wbuf+sizeof wbuf-wp);})
#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(){
	char*rp=getrp();
	rd_skip();
	long s=0,t=0;
	while(*rp){
		long x=rd();
		s+=x;
		t+=x*x;
	}
	wt1((s+1+MD-t%MD*inverse(s)%MD)%MD);
	_exit(0);
}