//poj 3154

//sep9

#include <iostream>

#include <cmath>

using namespace std;

double a[2048];

double b[2048];

int main()

{

	int n,m;

	while(scanf("%d%d",&n,&m)==2){

		for(int i=0;i<n;++i)

			a[i]=i*(10000.0/n);

		for(int i=0;i<(n+m);++i)

			b[i]=i*(10000.0/(n+m));

		double ans=0;

		for(int i=0;i<n;++i){

			double minx=9999999.9;

			for(int j=0;j<m+n;++j)

				minx=min(minx,fabs(a[i]-b[j]));

			ans+=minx;

		}

		printf("%.4lf\n",ans);

	}

	return 0;

}