include
include
using namespace std;
int main() {
int n;
cin >> n;
double e = 1.0;
double fact = 1.0; // 阶乘
for(int i = 1; i <= n; i++)
{
fact *= i; // 计算i!
e += 1.0 / fact;
}
// 输出小数点后10位
cout << fixed << setprecision(10) << e << endl;
return 0;
}