#pragma GCC optimize ("O3")
#pragma GCC target ("avx")
#include "bits/stdc++.h" // define macro "/D__MAI"

using namespace std;
typedef long long int ll;

#define xprintf(fmt,...) fprintf(stderr,fmt,__VA_ARGS__)
#define debugv(v) {printf("L%d %s > ",__LINE__,#v);for(auto e:v){cout<<e<<" ";}cout<<endl;}
#define debuga(m,w) {printf("L%d %s > ",__LINE__,#m);for(int x=0;x<(w);x++){cout<<(m)[x]<<" ";}cout<<endl;}
#define debugaa(m,h,w) {printf("L%d %s >\n",__LINE__,#m);for(int y=0;y<(h);y++){for(int x=0;x<(w);x++){cout<<(m)[y][x]<<" ";}cout<<endl;}}
#define ALL(v) (v).begin(),(v).end()
#define repeat(cnt,l) for(auto cnt=0ll;(cnt)<(l);++(cnt))
#define iterate(cnt,b,e) for(auto cnt=(b);(cnt)!=(e);++(cnt))
#define MD 1000000007ll
#define PI 3.1415926535897932384626433832795
#define EPS 1e-12
template<typename T1, typename T2> ostream& operator <<(ostream &o, const pair<T1, T2> p) { o << "(" << p.first << ":" << p.second << ")"; return o; }
template<typename iterator> inline size_t argmin(iterator begin, iterator end) { return distance(begin, min_element(begin, end)); }
template<typename iterator> inline size_t argmax(iterator begin, iterator end) { return distance(begin, max_element(begin, end)); }
template<typename T> T& maxset(T& to, const T& val) { return to = max(to, val); }
template<typename T> T& minset(T& to, const T& val) { return to = min(to, val); }
void bye(string s, int code = 0) { cout << s << endl; exit(0); }
mt19937_64 randdev(8901016);
inline ll rand_range(ll l, ll h) {
    return uniform_int_distribution<ll>(l, h)(randdev);
}

#ifdef __MAI
#define getchar_unlocked getchar
#define putchar_unlocked putchar
#endif
#ifdef __VSCC
#define getchar_unlocked _getchar_nolock
#define putchar_unlocked _putchar_nolock
#endif
namespace {
#define isvisiblechar(c) (0x21<=(c)&&(c)<=0x7E)
    class MaiScanner {
    public:
        template<typename T> void input_integer(T& var) {
            var = 0;
            T sign = 1;
            int cc = getchar_unlocked();
            for (; cc<'0' || '9'<cc; cc = getchar_unlocked())
                if (cc == '-') sign = -1;
            for (; '0' <= cc&&cc <= '9'; cc = getchar_unlocked())
                var = (var << 3) + (var << 1) + cc - '0';
            var = var*sign;
        }
        inline int c() { return getchar_unlocked(); }
        inline MaiScanner& operator>>(int& var) {
            input_integer<int>(var);
            return *this;
        }
        inline MaiScanner& operator>>(long long& var) {
            input_integer<long long>(var);
            return *this;
        }
        inline MaiScanner& operator>>(string& var) {
            int cc = getchar_unlocked();
            for (; !isvisiblechar(cc); cc = getchar_unlocked());
            for (; isvisiblechar(cc); cc = getchar_unlocked())
                var.push_back(cc);
            return *this;
        }
        template<typename IT> void in(IT begin, IT end) {
            for (auto it = begin; it != end; ++it) *this >> *it;
        }
    };
}
MaiScanner scanner;




typedef int boolean;

class EasyLP {
public:
    const int dimension;
    // 左辺
    vector<vector<double>> equation;
    // 定数項
    vector<double> offset;
    // 目的関数
    vector<double> objective;
    // 求まった目的関数の値
    double objective_c;

    EasyLP(int n) :dimension(n), objective(n) {
    }

    // 目的関数を最小化する．
    // 式の情報は書き換えられる．
    double minimize() {

        while (true) {
            // printTableau();
            // 目的関数の値を減少させることができる変数を探す
            int idx = 0;
            {
                double val = objective[0];
                for (int i = 1; i < dimension; ++i) {
                    if (val > objective[i]) {
                        val = objective[i];
                        idx = i;
                    }
                }
                // 無いなら最適解が得られた
                if (val >= 0) break;
            }

            // どの程度まで増やせば良いだろうか
            int target = -1;
            {
                double val, lim = 0;
                for (int i = 0; i < equation.size(); ++i) {
                    if (equation[i][idx] == 0) continue; // 0除算防止
                    val = offset[i] / equation[i][idx];
                    if (0 < val && (target == -1 || val < lim)) {
                        lim = val;
                        target = i;
                    }
                }
            };
            if (target == -1) break;
            {
                // ピボット係数
                double p = equation[target][idx];

                // ピボット係数を p で除算
                for (double& e : equation[target])
                    e /= p;
                offset[target] /= p;

                // ピボット列の掃き出し
                for (int i = 0; i < equation.size(); ++i) {
                    if (i == target) continue;

                    double d = equation[i][idx];
                    for (int j = 0; j < dimension; j++) {
                        if (j != idx)
                            equation[i][j] -= d * equation[target][j];
                        else
                            equation[i][j] = 0;
                    }

                    offset[i] -= d * offset[target];
                }
                {
                    double d = objective[idx];
                    for (int j = 0; j < dimension; j++) {
                        if (j != idx)
                            objective[j] -= d * equation[target][j];
                        else
                            objective[j] = 0;

                    }

                    objective_c += d * offset[target];
                }
            }
        }
        return -objective_c;
    }

    void printTableau() {
        for (int i = 0; i < equation.size(); ++i) {
            for (double a : equation[i]) {
                printf(" %7.2f", a);
            }
            printf(" | %7.2f\n", offset[i]);
        }
        for (int i = equation.size(); 0 <= i; --i) { printf("---------"); }
        printf("\n");
        for (double a : objective) {
            printf(" %7.2f", a);
        }
        printf(" %7.2f\n#####\n", objective_c);
    }
};

int main() {
    {
        // EasyLP lp(5);
        // lp.equation.push_back({ 60.0, 40.0,  1.0,  0.0, 0.0 }); lp.offset.push_back(3800.0);
        // lp.equation.push_back({ 20.0, 30.0,  0.0,  1.0, 0.0 }); lp.offset.push_back(2100.0);
        // lp.equation.push_back({ 20.0, 10.0,  0.0,  0.0, 1.0 }); lp.offset.push_back(1200.0);
        // lp.objective = { -400.0, -300.0, 0.0, 0.0, 0.0 };   lp.objective_c = 0.0;
        // 
        // printf("%.7f\n", lp.minimize());
    }


    int ic, id;

    scanner >> ic >> id;

    double c, d;
    c = ic;
    d = id;

    EasyLP lp(4);
    lp.equation.push_back({ 21.0, 8.0, 1.0, 0.0 }); lp.offset.push_back(28.0*c);
    lp.equation.push_back({ 7.0, 20.0, 0.0, 1.0 }); lp.offset.push_back(28.0*d);
    lp.objective = { -1000.0, -2000.0, 0.0, 0.0 };   lp.objective_c = 0.0;

    printf("%.7f\n", lp.minimize());

    //lp.printTableau();

    return 0;
}