#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; inline bool cheak(int x, int y, int xMax, int yMax){ return x >= 0 && y >= 0 && xMax > x && yMax > y; } template inline string toString(T x) { ostringstream sout; sout << x; return sout.str(); } template inline T sqr(T x) { return x*x; } typedef pair P; typedef tuple T; typedef long long ll; typedef unsigned long long ull; inline ll toInt(string s) { ll v; istringstream sin(s); sin >> v; return v; } #define For(i,a,b) for(int (i) = (a);i < (b);(i)++) #define rep(i,n) For(i,0,n) #define clr(a) memset((a), 0 ,sizeof(a)) #define mclr(a) memset((a), -1 ,sizeof(a)) #define all(a) (a).begin(),(a).end() #define sz(a) (sizeof(a)) #define Fill(a,v) fill((int*)a,(int*)(a+(sz(a)/sz(*(a)))),v) const int dx[8] = { 1, 0, -1, 0, 1, 1, -1, -1 }, dy[8] = { 0, -1, 0, 1, -1, 1, -1, 1 }; const int mod = 1000000007; const int INF = 1e9; int a[] = { 2, 3, 5, 7, 11, 13 }; int b[] = { 4, 6, 8, 9, 10, 12 }; int p,c; int d[20]; double sum = 0; void dfs(int t){ if (t == p + c){ double tmp = 1; rep(i, p + c)tmp *= d[i]; sum += tmp / pow(6,p+c); return; } rep(i, 6){ if (t < p) d[t] = a[i]; else d[t] = b[i - p]; dfs(t + 1); } } int main() { cin >> p >> c; dfs(0); cout << setprecision(40) << sum << endl; return 0; }