#include #define FOR(i, a, n) for(int (i) = (int)(a); (i) < (int)(n); ++(i)) #define FORe(i, a, n) for(int (i) = (int)(a); (i) <= (int)(n); ++(i)) #define rFOR(i, a, n) for(int (i) = (int)(n)-1; (i) >= (int)(a); --(i)) #define rFORe(i, a, n) for(int (i) = (int)(n); (i) >= (int)(a); --(i)) #define REP(i, n) FOR((i), 0, (n)) #define REPe(i, n) FORe((i), 1, (n)) #define REPo(i, n) FORe((i), 0, (n)) #define rREP(i, n) rFOR((i), 0, (n)) #define rREPe(i, n) rFORe((i), 1, (n)) #define rREPo(i, n) rFORe((i), 0, (n)) #define rep(i, n) FOR((i), 0, (n)) #define all(v) (v).begin(), (v).end() #define rall(v) (v).rbegin(), (v).rend() #define fi first #define se second #define dup(x, y) (((x)+(y)-1)/(y)) #define vc(T) vector #define vv(T) v(v(T)) using namespace std; using ll = long long; using P = pair; using pll = pair; using T = tuple; using vi = vector; using vvi = vector; using vl = vector; using vs = vector; using vp = vector

; using vt = vector; 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; } // auto mod int const int mod = 1000000007; // const int mod = 998244353; struct mint { ll x; // typedef long long ll; mint(ll x=0):x((x%mod+mod)%mod){} mint operator-() const { return mint(-x);} mint& operator+=(const mint a) { if ((x += a.x) >= mod) x -= mod; return *this; } mint& operator-=(const mint a) { if ((x += mod-a.x) >= mod) x -= mod; return *this; } mint& operator*=(const mint a) { (x *= a.x) %= mod; return *this;} mint operator+(const mint a) const { return mint(*this) += a;} mint operator-(const mint a) const { return mint(*this) -= a;} mint operator*(const mint a) const { return mint(*this) *= a;} mint pow(ll t) const { if (!t) return 1; mint a = pow(t>>1); a *= a; if (t&1) a *= *this; return a; } // for prime mod mint inv() const { return pow(mod-2);} mint& operator/=(const mint a) { return *this *= a.inv();} mint operator/(const mint a) const { return mint(*this) /= a;} }; istream& operator>>(istream& is, const mint& a) { return is >> a.x;} ostream& operator<<(ostream& os, const mint& a) { return os << a.x;} int main() { int n; cin>> n; vl c(n); vc(mint) a(n); REP(i, n) cin>>c[i]; REP(i, n) a[i] = c[i]; mint ans; for (int i = n-1; i > 0; i--) { REP(j, i) { a[j] += a[j+1]; } } cout << a[0] << endl; return 0; }