#define _CRT_SECURE_NO_WARNINGS #define _USE_MATH_DEFINES #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define REP(a,b) for(long long a = 0;a < b;++a) int main() { int n,b; cin >> n >> b; long double ans_sekibun = 0; long double ans_bibun = 0; REP(i, n) { double hogehoge = 0; cin >> hogehoge; ans_bibun += hogehoge*powl(b, hogehoge - 1); if (hogehoge != -1) { ans_sekibun += (1 / (hogehoge + 1))*pow(b, hogehoge + 1); } else { ans_sekibun += log(b); } } cout << ans_bibun <