#include <iostream>
using namespace std ;

int main() {
    int n;
    cin >> n;
    double S = 0.0;
    for(int i = 2; i <= 2 * n; i += 2) {
        S += ((double)(i - 1) / (double)(i * i));
        cout << i - 1 << "/" << i << " " << ((double)(i - 1) / (double)(i * i)) << endl;
    }
    cout << S << endl;
    return 0;
}