#include <cstdio>
using namespace std;

#define DIG 2000
#define LIM 2000
#define DEC 100000
#define DPOW 5

int edig[DIG], rdig[DIG];

int main() {
    int m;
    edig[0] = 2;
    rdig[0] = 1;
    for (int i = 2; i < LIM; i++) {
        m = 0;
        for (int j = 0; j < DIG; j++) {
            m = m * DEC + rdig[j];
            if (m < i) {
                rdig[j] = 0;
                continue;
            }
            rdig[j] = m / i;
            m = m % i;
        }
        m = rdig[DIG-1];
        for (int j = DIG - 1; j >= 0; j--) {
            m += rdig[j] + edig[j];
            edig[j] = m % DEC;
            m /= DEC;
        }
    }
    printf("%d.", edig[0]);
    for (int j = 1; j < DIG; j++)
        printf("%05d", edig[j]);
    return 0;
}