#include <stdio.h>
int main()
{
    int n, fg = 1;
    scanf("%d", &n);
    double result;
    for (int i = 1; i <= n; i++)
    {
        result += fg * 1.0 / i;
        fg = -fg;
    }
    printf("%.8f\n", result);
    return 0;
}