#include #include using namespace std; using namespace atcoder; istream &operator>>(istream &is, modint &a) { long long v; is >> v; a = v; return is; } ostream &operator<<(ostream &os, const modint &a) { return os << a.val(); } istream &operator>>(istream &is, modint998244353 &a) { long long v; is >> v; a = v; return is; } ostream &operator<<(ostream &os, const modint998244353 &a) { return os << a.val(); } istream &operator>>(istream &is, modint1000000007 &a) { long long v; is >> v; a = v; return is; } ostream &operator<<(ostream &os, const modint1000000007 &a) { return os << a.val(); } typedef long long ll; typedef vector> Graph; typedef pair pii; typedef pair pll; #define FOR(i,l,r) for (int i = l;i < (int)(r); i++) #define rep(i,n) for (int i = 0;i < (int)(n); i++) #define all(x) x.begin(), x.end() #define rall(x) x.rbegin(), x.rend() #define my_sort(x) sort(x.begin(), x.end()) #define my_max(x) *max_element(all(x)) #define my_min(x) *min_element(all(x)) template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } const int INF = (1<<30) - 1; const ll LINF = (1LL<<62) - 1; const int MOD2 = 1e9+7; const double PI = acos(-1); vector di = {1,0,-1,0}; vector dj = {0,1,0,-1}; #ifdef LOCAL # include # define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__) #else # define debug(...) (static_cast(0)) #endif //https://drken1215.hatenablog.com/entry/2018/06/08/210000 //COMinit()を忘れない!!! const ll NMAX = 404040; const ll MOD = 998244353; //const int MOD = 1e9+7; ll fac[NMAX],finv[NMAX],inv[NMAX]; void COMinit(){ fac[0] = fac[1] = 1LL; finv[0] = finv[1] = 1LL; inv[1] = 1LL; for (int i=2;i> N; vector A(N); rep(i, N) cin >> A[i]; // vector dp(N + 1, vector(N + 1)); // dp[0][0] = 1; // for(int i = 1; i <= N; i++){ // for(int j = i - 1; j <= N; j++){ // dp[i][j] = dp[i - 1][j]; // if(j) dp[i][j] += dp[i][j - 1]; // } // } // debug(dp); // debug(dp[N][N]); mint ans = 0; rep(i, N) { int n = N - i - 1, m = N - 1; mint coef = (mint)(m - n + 1) / (mint)(m + 1) * (mint)nCr(m + n, m); ans += coef * A[i]; debug(i, ans, coef); } cout << ans << endl; }