#include<iostream>
#include<iomanip>
#include<cstdio>
#include<algorithm>
using namespace std;
long A,B;
long gcd(long a,long b){
	if(a<0)a=-a;
	if(b<0)b=-b;
	if(a<b)swap(a,b);
	if(a==b||b==0)return a+b;
	return gcd(a-2*b,b);
}
main()
{
	cin>>A>>B;
	long g=gcd(A,B);
	double ans=1./4;
	if(g)
	{
		for(int i=3;;i++)
		{
			long u=2+g*(i-2);
			if(u>20)break;
			double now=i-1;
			for(int j=0;j<u;j++)now/=u;
			ans+=now;
		}
	}
	cout<<fixed<<setprecision(16)<<ans<<endl;
}