public class Main {
public static double func(int i,int j) {
double ret = 1.0/i - 1.0/j;
return ret;
}
public static void main(String[] args) {
double sum = 0.0;
for (int i = 1; i < 100 ; i+=2) {
sum = sum+ func(i,i+1);
}
System.out.println(sum);
}