#include #include #include #include #include #include #include #include #include #include #include #include #define rep(i,N) for (ll i = 0; i < (N); i++) #define repone(i,N) for(ll i = 1; i < (N); i++) #define REP(i,N) for (ll i = (N)-1; i >= 0; i--) #define FOR(j,i,N) for (ll j = (N)-1; j > (i); j--) #define repsqrt(i,N) for(ll i = 1; i*i <= (N); i++) #define updown(i,a,b) for(ll i = (a)-1; i < (b); i++) #define ST string #define vec vector #define vecs vector #define outb(s) cout << fixed << setprecision(15) << s << endl; #define out(s) cout << s << endl; #define Graph vector> #define vecb vector using ll = long long; using lb = long double; using l = int; using namespace std; const ll mod = 1000000007; const ll ze = 0; const lb zeb = 0.0; const ll on = 1; const ll INF = 1e8; const lb pi = 3.14159265358979; using ll = long long; using lb = long double; ll nCk(ll N, ll K){ if(N>1){ ll kid = 1; for(ll i = N; i > N - K; i--){ kid = kid * i; } for(ll i = 1; i < K + 1; i++){ kid = kid / i; } return kid; } else{ return 0; } } ll stair_pow(ll N){// 階乗 ll sum = 1; for(ll i = 1; i <= N; i++){ sum = sum * i % mod; } return sum % mod; } ll gcd(ll P, ll Q){ return Q ? gcd(Q,P % Q):P; } ll lcm(ll P, ll Q){ return P / gcd(P,Q) * Q; } bool is_prime(ll x){ if(x <= 1){ return false; } for(ll i=2; i * i <= x; i++){ if(x%i==0){ return false; } } return true; } ll sum_of_num(ll num){// 各位の和 ll dig; ll sum = 0; while(num){ dig = num % 10; sum = sum + dig; num = num / 10; } return sum; } ll how_many_break(ll n, ll m){// 何回割れるか ll counter = 0; while (n % m == 0){ n = n / m; counter++; } return counter; } ll many_pow(ll N, ll M){ // NのM乗 if(M == 0)return 1; else{ ll sum = 1; for(ll i = 0; i < M; i++){ sum *= N; } return sum; } } ll one_to_i(ll i){ // 1からiまでの和 if(i < 0){ return 0; } else{ return i*(i+1)/2; } } ll how_many_yaku(ll num){ ll ans = 0; rep(i,num){ if(num % (i+1) == 0)ans++; } return ans; } ll Digit(ll num){ ll digit=0; while(num!=0){ num /= 10; digit++; } return digit; } ll binary_search(ll left, ll right, ll N){ ll count = 0; while (right - left > 1) { ll mid = left + (right - left) / 2; if (mid <= N) left = mid; else right = mid; count++; } return count; } /*-----------------------------------------------------------------------------------*/ // cout << fixed << setprecision(15) // continue // count(S.begin(),S.end(),''); // reverse(S.begin(), S.end()); // S.substr(8, 8) // sort(p.begin(), p.end()); // sort(p.rbegin(), p.rend()); ← 降順sort. /*-----------------------------------------------------------------------------------*/ /*備忘録*/ /*-----------------------------------------------------------------------------------*/ //・n⊕n=0 //・n⊕(n+1)=1 (n∊偶数) /*-----------------------------------------------------------------------------------*/ int main(){ ll n; cin >> n; ll ans = 0; rep(i,n){ ll a; cin >> a; if(i==0 || i==n-1){ ans += a; } else{ ans += a*(n-1); } ans %= mod; } out(ans); return 0; }