#include <iostream>
#include<iomanip>
#include<cmath>
#include<string>
using namespace std;
/*
Napisite program koji omogucava unos broja n preko tastature te izracnava sumu:
S=1-(1+2/2!)+(1+2+3/3!)-....+(-1)NAn-1*(1+2+3+...+n)/n!
*/
void Suma(int, double &);
int fakt(int);

void main()
{
    int n;
    cin >> n;
    double s = 0;
    Suma(n, s);
    cout << "suma: " <<s<< endl;

}

void Suma(int n, double &s)
{
    double x = 0;
    for (int i = 1; i <=n; i++)
    {
        s += pow(-1, (i - 1))*((x + i) / fakt(i));
        x = x + i;
    }
}

int fakt(int i)
{
    int f = 1;
    for (int i = 1; i <=i; i++)
    {
        f *= i;
    }
    return f;
}