#include <stdio.h>
#include <math.h>

int main() {
    int n = 0;
    scanf("%d", &n);
    int i = 0;
    double sum = 0;
    for(i = 1; i <= n; i++){
        sum = sum + pow(i,-1);
    }
    printf("%lf", sum);
    return 0;
}