#include<cstdio>

 #include<iostream>

 #include<cstring>

 #include<string>

 #include<cstdlib>

 #include<cmath>

 #include<sstream>

 #include<algorithm>

 #include<set>

 #include<stack>

 #include<list>

 #include<map>

 #include<queue>

 #include<deque>

 #include<vector>

 #include<cctype>

 using namespace std;

 const int MAXN =  + ;

 const int MAXT =  + ;

 const int INF = 0x7f7f7f7f;

 const double EPS = 1e-;

 const double PI = acos(-1.0);

 typedef long long ll;

 typedef unsigned long long llu;

 int main()

 {

     int n, m;

     while(scanf("%d%d", &n, &m) != EOF)

     {

         double ans = ;

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

         {

             double tmp = (double)i / n * (n + m);//所有待移动雕塑在n+m的等距分布里的坐标

             ans += fabs(tmp - floor(tmp + 0.5)) / (n + m);//除以n+m，是使ans的结果是以总长度为1为基准，而不是n+m

         }

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

     }

     return ;

 }