4.2.16

#include <iostream>
#include <cmath>

using namespace std;

int main()
{
    int n,i=1;
    double sum=1,Znamenetion=i;
    cin>>n;

    while(i<=n)
    {
        Znamenetion*=i;
        sum+=1/Znamenetion;
        i++;
    }
    cout<<sum;
    return 0;
}