#include <stdio.h>
float sumnum (int n){
    float sum = 0.0;
    for(int i =1;i<=n;i++){
        sum=sum+1.0/i;
    }
    return sum;
}
int main() {
    int n;
    scanf("%d",&n);
    float sum = sumnum(n);
    printf("%.6f",sum);
    return 0;
}