import java.util.*;
import java.lang.*;
import java.io.*;

class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
		double S=0, m, n;
		m=in.nextInt();
		n=in.nextInt();
		for(int i=1;i<=m;i++){
    			for(int j=1;j<=n;j++){
        				S+=1.0/(i+j*j);
    			}
    		}
    		System.out.print(S);
    	}
}