/*
 * Programmieren fuer Physiker, WS 2009/10
 *
 * Klausur, Aufg. 1
 */

#include <iostream>
#include <cmath>
using namespace std ;

int main()
{
    int n ;
    double sum=0.0 ;
      
    cout << "Aufg1: Summenberechnung" << endl ;
    cout << "obere Summengrenze: " ;
    cin >> n ;

    for (int i=1; i<=n; i++) 
	sum += 1.0/(double(i)*double(i)) ;
    
    cout << "Die Summe ist: " << sum << endl ;
}