import std.stdio, std.conv, std.functional, std.string; import std.algorithm, std.array, std.container, std.range, std.typecons; import std.bigint, std.numeric, std.math, std.random; import core.bitop; string FMT_F = "%.10f"; static File _f; void file_io(string fn) { _f = File(fn, "r"); } static string[] s_rd; T _RD(T = long)() { while(!s_rd.length) s_rd = readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; } T _RD(T = long)(File f) { while(!s_rd.length) s_rd = f.readln.chomp.split; string res = s_rd[0]; s_rd.popFront; return res.to!T; } T[] _RDA(T = long)(T fix = 0) { auto r = readln.chomp.split.to!(T[]); r[] += fix; return r; } T[] _RDA(T = long)(File f, T fix = 0) { auto r = f.readln.chomp.split.to!(T[]); r[] += fix; return r; } T RD(T = long)() { if (_f.isOpen) return _RD!T(_f); else return _RD!T; } T[] RDA(T = long)(T fix = 0) { if (_f.isOpen) return _RDA!T(_f, fix); else return _RDA!T(fix); } size_t[] MAKE_IDX(alias less = "a < b", Range)(Range range) { auto idx = new size_t[](range.length); makeIndex!(less)(range, idx); return idx;} size_t MIN_POS(alias less = "a < b", Range)(Range range) { auto r = minPos!(less)(range); return range.length - r.length; } void chmin(T)(ref T x, T y) { x = min(x, y); } void chmax(T)(ref T x, T y) { x = max(x, y); } bool inside(T)(T x, T b, T e) { return x >= b && x < e; } T lcm(T)(T x, T y) { return x * (y / gcd(x, y)); } long mod = 10^^9 + 7; //long mod = 998_244_353; //long mod = 1_000_003; void moda(T)(ref T x, T y) { x = (x + y) % mod; } void mods(T)(ref T x, T y) { x = ((x + mod) - (y % mod)) % mod; } void modm(T)(ref T x, T y) { x = (x * y) % mod; } void modpow(T)(ref T x, T y) { if (!y) { x = 1; return; } auto t = x; x.modpow(y>>1); x.modm(x); if (y&1) x.modm(t); } void modd(T)(ref T x, T y) { y.modpow(mod - 2); x.modm(y); } struct Cmb { void init(long n) { long powmod(long a, long p) { long ans = 1; long mul = a; while (p > 0) { if ((p & 1) == 1) ans.modm(mul); p >>= 1; mul.modm(mul); } return ans; } ++n; fact = new long[2][](n); fact[0][0] = 1; foreach (i; 1..n) { fact[i][0] = fact[i-1][0]; fact[i][0].modm(i); } fact[n-1][1] = powmod(fact[n-1][0], mod - 2); foreach_reverse (i; 0..n-1) { fact[i][1] = fact[i+1][1]; fact[i][1].modm(i+1); } } long get(long n, long r) { long res = fact[n][0]; res.modm(fact[r][1]); res.modm(fact[n-r][1]); return res; } long[2][] fact; } void main() { auto N = RD; auto A = RDA; long ans; Cmb cmb; cmb.init(N); foreach (i; 0..N) { auto tmp = A[i]; tmp.modm(cmb.get(N-1, i)); ans.moda(tmp); } writeln(ans); stdout.flush; debug readln; }