// 8 zadacha
#include <iostream>
#include <cmath>
using namespace std;
long double fact(int N)
{
    if (N == 0)
        return 1;
    else
        return N * fact(N - 1);
}

int main()
{
    int x;

    int i = 2;
    scanf("%i", &x);
    float cnt = 1 + x;
    float eps = 10;
    while (cnt < eps) {
        cnt = cnt + (pow(x, i) / fact(i));
        i++;
    }
    printf("%.3f", cnt);


}