// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;



using i64 = int64_t;



#define rep(i, x, y) for (i64 i = i64(x), i##_max_for_repmacro = i64(y); i < i##_max_for_repmacro; ++i)

#define debug(x) #x << "=" << (x)



#ifdef DEBUG

#define _GLIBCXX_DEBUG

#define print(x) std::cerr << debug(x) << " (L:" << __LINE__ << ")" << std::endl

#else

#define print(x)

#endif



template <i64 p>

class fp {

public:

    i64 x;

    fp() : x(0) {}

    fp(i64 x_) : x((x_ % p + p) % p) {}

    fp operator+() const { return fp(x); }

    fp operator-() const { return fp(-x); }

    fp& operator+=(const fp& y) {

        x += y.x;

        if (x >= p) x -= p;

        return *this;

    }

    fp& operator-=(const fp& y) { return *this += -y; }

    fp& operator*=(const fp& y) {

        x = x * y.x % p;

        return *this;

    }

    fp& operator/=(const fp& y) { return *this *= fp(inverse(y.x)); }

    fp operator+(const fp& y) const { return fp(x) += y; }

    fp operator-(const fp& y) const { return fp(x) -= y; }

    fp operator*(const fp& y) const { return fp(x) *= y; }

    fp operator/(const fp& y) const { return fp(x) /= y; }

    bool operator==(const fp& y) const { return x == y.x; }

    bool operator!=(const fp& y) const { return !(*this == y); }

    i64 extgcd(i64 a, i64 b, i64& x, i64& y) {

        i64 d = a;

        if (b != 0) {

            d = extgcd(b, a % b, y, x);

            y -= (a / b) * x;

        } else {

            x = 1;

            y = 0;

        }

        return d;

    }

    i64 inverse(i64 a) {

        i64 x, y;

        extgcd(a, p, x, y);

        return (x % p + p) % p;

    }

};



template <i64 p>

i64 abs(const fp<p>& x) { return x.x; }



template <i64 p>

ostream& operator<<(ostream& os, const fp<p>& x) {

    os << x.x;

    return os;

}



template <typename T, typename U>

ostream& operator<<(ostream& os, const pair<T, U>& p) {

    os << "(" << p.first << ", " << p.second << ")";

    return os;

}



template <typename T>

ostream& operator<<(ostream& os, const vector<T>& vec) {

    os << "[";

    for (const auto& v : vec) {

        os << v << ",";

    }

    os << "]";

    return os;

}



template <typename T>

bool chmin(T& a, const T& b) {

    if (a > b) {

        a = b;

        return true;

    }

    return false;

}



template <typename T>

bool chmax(T& a, const T& b) {

    if (a < b) {

        a = b;

        return true;

    }

    return false;

}



template <typename A, typename T, size_t size>

void fill(A (&ary)[size], const T& val) {

    fill((T*)ary, (T*)(ary + size), val);

}



// x未満の要素の個数を返す

template <typename T>

i64 count_less(const vector<T>& v, T x) {

    return lower_bound(begin(v), end(v), x) - begin(v);

}



// x以下の要素の個数を返す

template <typename T>

i64 count_less_or_equal(const vector<T>& v, T x) {

    return upper_bound(begin(v), end(v), x) - begin(v);

}



// xより大きい要素の個数を返す

template <typename T>

i64 count_greater(const vector<T>& v, T x) {

    return end(v) - upper_bound(begin(v), end(v), x);

}



// x以上の要素の個数を返す

template <typename T>

i64 count_greater_or_equal(const vector<T>& v, T x) {

    return end(v) - lower_bound(begin(v), end(v), x);

}



// x未満の要素のうち最大のものを返す

template <typename T>

T max_less(const vector<T>& v, T x) {

    return *(lower_bound(begin(v), end(v), x) - 1);

}



// x以下の要素のうち最大のものを返す

template <typename T>

T max_less_or_equal(const vector<T>& v, T x) {

    return *(upper_bound(begin(v), end(v), x) - 1);

}



// xより大きい要素のうち最小のものを返す

template <typename T>

T min_greater(const vector<T>& v, T x) {

    return *upper_bound(begin(v), end(v), x);

}



// x以上の要素のうち最小のものを返す

template <typename T>

T min_greater_or_equal(const vector<T>& v, T x) {

    return *lower_bound(begin(v), end(v), x);

}



constexpr int inf = 1.01e9;

constexpr i64 inf64 = 4.01e18;

constexpr long double eps = 1e-9;



int sgn(const long double& a, const long double& epsilon = eps) {

    if (a < -epsilon) return -1;

    if (a > epsilon) return 1;

    return 0;

}



long double tolerance(const long double& a, const long double& b, const long double& epsilon = eps) {

    return epsilon * max({1.l, abs(a), abs(b)});

}



// a==bか?

bool is_equal(const long double& a, const long double& b, const long double& epsilon = eps) {

    return abs(a - b) <= tolerance(a, b, epsilon);

}



// a<bか?

bool is_less(const long double& a, const long double& b, const long double& epsilon = eps) {

    return a < b - tolerance(a, b, epsilon);

}



// a<=bか?

bool is_less_or_equal(const long double& a, const long double& b, const long double& epsilon = eps) {

    //return is_less(a, b, epsilon) or is_equal(a, b, epsilon);

    return a<=b+tolerance(a,b,epsilon);

}



// a>bか?

bool is_greater(const long double& a, const long double& b, const long double& epsilon = eps) {

    return a > b + tolerance(a, b, epsilon);

}



// a>=bか?

bool is_greater_or_equal(const long double& a, const long double& b, const long double& epsilon = eps) {

    return is_greater(a, b, epsilon) or is_equal(a, b, epsilon);

}



typedef complex<long double> point;

typedef pair<point, point> line;

point polar(const long double& r, const long double& th) { return point(r * cosl(th), r * sinl(th)); }

bool equal(const long double x1, const long double x2) { return abs(x1 - x2) < eps; }

bool equal(const point& a, const point& b) { return equal(a.real(), b.real()) and equal(a.imag(), b.imag()); }

long double length(const point& a) { return abs(a); }

long double distance(const point& a, const point& b) { return abs(a - b); }

long double dot(const point& a, const point& b) { return a.real() * b.real() + a.imag() * b.imag(); }

long double cross(const point& a, const point& b) { return a.real() * b.imag() - a.imag() * b.real(); }

bool is_orthogonal(const point& a1, const point& a2, const point& b1, const point& b2) { return equal(dot(a1 - a2, b1 - b2), 0.0); }

bool is_orthogonal(const line& l, const line& m) { return is_orthogonal(l.first, l.second, m.first, m.second); }

bool is_parallel(const point& a1, const point& a2, const point& b1, const point& b2) { return equal(cross(a1 - a2, b1 - b2), 0.0); }

bool is_parallel(const line& l, const line& m) { return is_parallel(l.first, l.second, m.first, m.second); }

int ccw(point a, point b, point c) {

    b -= a;

    c -= a;

    if (cross(b, c) > 0) return +1;    // counter clockwise

    if (cross(b, c) < 0) return -1;    // clockwise

    if (dot(b, c) < 0) return +2;      // c--a--b on line

    if (norm(b) < norm(c)) return -2;  // a--b--c on line

    return 0;

}

bool intersectLL(const line& l, const line& m) {

    return abs(cross(l.second - l.first, m.second - m.first)) > eps ||  // non-parallel

           abs(cross(l.second - l.first, m.first - l.first)) < eps;     // same line

}

bool intersectLS(const line& l, const line& s) {

    return cross(l.second - l.first, s.first - l.first) *  // s.first is left of l

           cross(l.second - l.first, s.second - l.first) <

           eps;  // s.second is right of l

}

bool intersectLP(const line& l, const point& p) {

    return abs(cross(l.second - p, l.first - p)) < eps;

}

bool intersectSS(const line& s, const line& t) {

    return ccw(s.first, s.second, t.first) * ccw(s.first, s.second, t.second) <= 0 &&

           ccw(t.first, t.second, s.first) * ccw(t.first, t.second, s.second) <= 0;

}

bool intersectSP(const line& s, const point& p) {

    return abs(s.first - p) + abs(s.second - p) - abs(s.second - s.first) < eps;  // triangle inequality

}

point projection(const line& l, const point& p) {

    long double t = dot(p - l.first, l.first - l.second) / norm(l.first - l.second);

    return l.first + t * (l.first - l.second);

}

point reflection(const line& l, const point& p) {

    return p + point((projection(l, p) - p).real() * 2, (projection(l, p) - p).imag() * 2);

}

long double distanceLP(const line& l, const point& p) {

    return abs(p - projection(l, p));

}

long double distanceLL(const line& l, const line& m) {

    return intersectLL(l, m) ? 0 : distanceLP(l, m.first);

}

long double distanceLS(const line& l, const line& s) {

    if (intersectLS(l, s)) return 0;

    return min(distanceLP(l, s.first), distanceLP(l, s.second));

}

long double distanceSP(const line& s, const point& p) {

    const point r = projection(s, p);

    if (intersectSP(s, r)) return abs(r - p);

    return min(abs(s.first - p), abs(s.second - p));

}

long double distanceSS(const line& s, const line& t) {

    if (intersectSS(s, t)) return 0;

    return min(min(distanceSP(s, t.first), distanceSP(s, t.second)),

               min(distanceSP(t, s.first), distanceSP(t, s.second)));

}

// a1,a2を通る直線とb1,b2を通る直線の交点計算

point intersection_l(const point& a1, const point& a2, const point& b1, const point& b2) {

    const point &a = a2 - a1, b = b2 - b1;

    return a1 + a * cross(b, b1 - a1) / cross(b, a);

}

point intersection_l(const line& l, const line& m) {

    return intersection_l(l.first, l.second, m.first, m.second);

}



//直線の単位法線ベクトルを求める

line get_unit_normalV(const point& a, const point& b) {

    line l;

    l.first = ((b - a) * point(0, 1)) / abs(b - a);

    l.second = ((b - a) * point(0, -1)) / abs(b - a);

    return l;

}



//線分sを距離dだけ平行移動

pair<line, line> get_translation(const line& s, long double d) {

    line v = get_unit_normalV(s.first, s.second);

    pair<line, line> res;

    res.first = line(s.first + v.first * d, s.second + v.first * d);

    res.second = line(s.first + v.second * d, s.second + v.second * d);

    return res;

}



struct circle {

    point o;

    long double r;

    circle() {}

    circle(const point o, const long double r) : o(o), r(r) {}

};



//2円の交差判定

int icc(const circle &c, const circle &d) {

    /*

      1 : intersect

      0 : distinct

      -1: c < d

      -2: c > d



      intersect or contain : true

      distinct             : false

    */

    long double od = abs((c.o - d.o));

    return c.r + d.r < od + eps ? 0 : od + c.r < d.r + eps ? -1 : od + d.r < c.r + eps ? -2 : 1;

}



pair<point, point> ccc(const circle &c1, const circle &c2) {

    if (!icc(c1, c2)) return pair<point, point>(c1.o, c2.o);

    long double w = abs(c2.o - c1.o), th = arg(c2.o - c1.o);

    long double dth = acosl((c1.r * c1.r + w * w - c2.r * c2.r) / (2. * c1.r * w));

    return pair<point, point>(c1.o + polar(c1.r, th - dth), c1.o + polar(c1.r, th + dth));

}



void solve() {

    //constexpr i64 mod = 1'000'000'007;

    i64 N,K;

    cin >> N >> K;



    vector<long double> x(N),y(N),c(N);

    vector<point> xy;



    rep(i,0,N){

        cin >> x[i] >> y[i] >> c[i];

        xy.emplace_back(point(x[i],y[i]));

    }



    if(K==1){

        cout << 0 << endl;

        return;

    }



    auto ok=[&](long double t){

        vector<point> os;



        rep(i,0,N){

            rep(j,i+1,N){

                const auto p=xy[i],q=xy[j];

                const long double pd=t/c[i],qd=t/c[j];

                const circle pc(p,pd),qc(q,qd);



                const auto s=icc(pc,qc);

                if(s==0) continue;

                if(s==-1){

                    os.emplace_back(p);

                    continue;

                }

                if(s==-2){

                    os.emplace_back(q);

                    continue;

                }

                const auto tmp=ccc(pc,qc);

                os.emplace_back(tmp.first);

                os.emplace_back(tmp.second);

            }

        }



        bool res=false;

        for(const auto& o:os){

            i64 cnt=0;

            rep(i,0,N){

                const auto& p=xy[i];

                const long double d=distance(o,p);

                if(c[i]*d<=t+tolerance(c[i]*d,t)) ++cnt;

            }

            if(cnt>=K){

                res=true;

                break;

            }

        }



        return res;

    };



    long double lb=0,ub=inf64;

    rep(loop,0,200){

        long double t=(lb+ub)/2;

        if(ok(t)) ub=t;

        else lb=t;

    }



    cout << ub << endl;

}



int main() {

    std::cin.tie(0);

    std::ios::sync_with_stdio(false);

    cout.setf(ios::fixed);

    cout.precision(16);

    solve();

    return 0;

}


// Faster C++ solution for the same problem (measured speedup: 1.362542783978167x):
#include <bits/stdc++.h>

using namespace std;



using i64 = int64_t;



#define rep(i, x, y) for (i64 i = i64(x), i##_max_for_repmacro = i64(y); i < i##_max_for_repmacro; ++i)

#define debug(x) #x << "=" << (x)



#ifdef DEBUG

#define _GLIBCXX_DEBUG

#define print(x) std::cerr << debug(x) << " (L:" << __LINE__ << ")" << std::endl

#else

#define print(x)

#endif



template <i64 p>

class fp {

public:

    i64 x;

    fp() : x(0) {}

    fp(i64 x_) : x((x_ % p + p) % p) {}

    fp operator+() const { return fp(x); }

    fp operator-() const { return fp(-x); }

    fp& operator+=(const fp& y) {

        x += y.x;

        if (x >= p) x -= p;

        return *this;

    }

    fp& operator-=(const fp& y) { return *this += -y; }

    fp& operator*=(const fp& y) {

        x = x * y.x % p;

        return *this;

    }

    fp& operator/=(const fp& y) { return *this *= fp(inverse(y.x)); }

    fp operator+(const fp& y) const { return fp(x) += y; }

    fp operator-(const fp& y) const { return fp(x) -= y; }

    fp operator*(const fp& y) const { return fp(x) *= y; }

    fp operator/(const fp& y) const { return fp(x) /= y; }

    bool operator==(const fp& y) const { return x == y.x; }

    bool operator!=(const fp& y) const { return !(*this == y); }

    i64 extgcd(i64 a, i64 b, i64& x, i64& y) {

        i64 d = a;

        if (b != 0) {

            d = extgcd(b, a % b, y, x);

            y -= (a / b) * x;

        } else {

            x = 1;

            y = 0;

        }

        return d;

    }

    i64 inverse(i64 a) {

        i64 x, y;

        extgcd(a, p, x, y);

        return (x % p + p) % p;

    }

};



template <i64 p>

i64 abs(const fp<p>& x) { return x.x; }



template <i64 p>

ostream& operator<<(ostream& os, const fp<p>& x) {

    os << x.x;

    return os;

}



template <typename T, typename U>

ostream& operator<<(ostream& os, const pair<T, U>& p) {

    os << "(" << p.first << ", " << p.second << ")";

    return os;

}



template <typename T>

ostream& operator<<(ostream& os, const vector<T>& vec) {

    os << "[";

    for (const auto& v : vec) {

        os << v << ",";

    }

    os << "]";

    return os;

}



template <typename T>

bool chmin(T& a, const T& b) {

    if (a > b) {

        a = b;

        return true;

    }

    return false;

}



template <typename T>

bool chmax(T& a, const T& b) {

    if (a < b) {

        a = b;

        return true;

    }

    return false;

}



template <typename A, typename T, size_t size>

void fill(A (&ary)[size], const T& val) {

    fill((T*)ary, (T*)(ary + size), val);

}



// x未満の要素の個数を返す

template <typename T>

i64 count_less(const vector<T>& v, T x) {

    return lower_bound(begin(v), end(v), x) - begin(v);

}



// x以下の要素の個数を返す

template <typename T>

i64 count_less_or_equal(const vector<T>& v, T x) {

    return upper_bound(begin(v), end(v), x) - begin(v);

}



// xより大きい要素の個数を返す

template <typename T>

i64 count_greater(const vector<T>& v, T x) {

    return end(v) - upper_bound(begin(v), end(v), x);

}



// x以上の要素の個数を返す

template <typename T>

i64 count_greater_or_equal(const vector<T>& v, T x) {

    return end(v) - lower_bound(begin(v), end(v), x);

}



// x未満の要素のうち最大のものを返す

template <typename T>

T max_less(const vector<T>& v, T x) {

    return *(lower_bound(begin(v), end(v), x) - 1);

}



// x以下の要素のうち最大のものを返す

template <typename T>

T max_less_or_equal(const vector<T>& v, T x) {

    return *(upper_bound(begin(v), end(v), x) - 1);

}



// xより大きい要素のうち最小のものを返す

template <typename T>

T min_greater(const vector<T>& v, T x) {

    return *upper_bound(begin(v), end(v), x);

}



// x以上の要素のうち最小のものを返す

template <typename T>

T min_greater_or_equal(const vector<T>& v, T x) {

    return *lower_bound(begin(v), end(v), x);

}



constexpr int inf = 1.01e9;

constexpr i64 inf64 = 4.01e18;

constexpr long double eps = 1e-9;



// 実数値のn分探索のループ回数の上限(2分探索なら50でも十分かもしれない)

constexpr i64 max_loop = 100;



long double tolerance(const long double& a, const long double& b, const long double& epsilon = eps) {

    return epsilon * max({1.l, abs(a), abs(b)});

}



// a<0なら-1, a==0なら0, a>0なら1

int sgn(const long double a, const long double& epsilon = eps) {

    return (a > epsilon) - (a < -epsilon);

}



// a<bなら-1, a==bなら0, a>bなら1

int compare(const long double& a, const long double& b, const long double& epsilon = eps) {

    return sgn(a - b, tolerance(a, b, epsilon));

}



// a==bか?

bool is_equal(const long double& a, const long double& b, const long double& epsilon = eps) {

    return compare(a,b,epsilon) == 0;

}



// a<bか?

bool is_less(const long double& a, const long double& b, const long double& epsilon = eps) {

    return compare(a,b,epsilon) == -1;

}



// a<=bか?

bool is_less_or_equal(const long double& a, const long double& b, const long double& epsilon = eps) {

    return compare(a,b,epsilon) <= 0;

}



// a>bか?

bool is_greater(const long double& a, const long double& b, const long double& epsilon = eps) {

    return compare(a,b,epsilon) == 1;

}



// a>=bか?

bool is_greater_or_equal(const long double& a, const long double& b, const long double& epsilon = eps) {

    return compare(a,b,epsilon) >= 0;

}



typedef complex<long double> point;

typedef pair<point, point> line;

point polar(const long double& r, const long double& th) { return point(r * cosl(th), r * sinl(th)); }

bool equal(const long double x1, const long double x2) { return abs(x1 - x2) < eps; }

bool equal(const point& a, const point& b) { return equal(a.real(), b.real()) and equal(a.imag(), b.imag()); }

long double length(const point& a) { return abs(a); }

long double distance(const point& a, const point& b) { return abs(a - b); }

long double dot(const point& a, const point& b) { return a.real() * b.real() + a.imag() * b.imag(); }

long double cross(const point& a, const point& b) { return a.real() * b.imag() - a.imag() * b.real(); }

bool is_orthogonal(const point& a1, const point& a2, const point& b1, const point& b2) { return equal(dot(a1 - a2, b1 - b2), 0.0); }

bool is_orthogonal(const line& l, const line& m) { return is_orthogonal(l.first, l.second, m.first, m.second); }

bool is_parallel(const point& a1, const point& a2, const point& b1, const point& b2) { return equal(cross(a1 - a2, b1 - b2), 0.0); }

bool is_parallel(const line& l, const line& m) { return is_parallel(l.first, l.second, m.first, m.second); }

int ccw(point a, point b, point c) {

    b -= a;

    c -= a;

    if (cross(b, c) > 0) return +1;    // counter clockwise

    if (cross(b, c) < 0) return -1;    // clockwise

    if (dot(b, c) < 0) return +2;      // c--a--b on line

    if (norm(b) < norm(c)) return -2;  // a--b--c on line

    return 0;

}

bool intersectLL(const line& l, const line& m) {

    return abs(cross(l.second - l.first, m.second - m.first)) > eps ||  // non-parallel

           abs(cross(l.second - l.first, m.first - l.first)) < eps;     // same line

}

bool intersectLS(const line& l, const line& s) {

    return cross(l.second - l.first, s.first - l.first) *  // s.first is left of l

           cross(l.second - l.first, s.second - l.first) <

           eps;  // s.second is right of l

}

bool intersectLP(const line& l, const point& p) {

    return abs(cross(l.second - p, l.first - p)) < eps;

}

bool intersectSS(const line& s, const line& t) {

    return ccw(s.first, s.second, t.first) * ccw(s.first, s.second, t.second) <= 0 &&

           ccw(t.first, t.second, s.first) * ccw(t.first, t.second, s.second) <= 0;

}

bool intersectSP(const line& s, const point& p) {

    return abs(s.first - p) + abs(s.second - p) - abs(s.second - s.first) < eps;  // triangle inequality

}

point projection(const line& l, const point& p) {

    long double t = dot(p - l.first, l.first - l.second) / norm(l.first - l.second);

    return l.first + t * (l.first - l.second);

}

point reflection(const line& l, const point& p) {

    return p + point((projection(l, p) - p).real() * 2, (projection(l, p) - p).imag() * 2);

}

long double distanceLP(const line& l, const point& p) {

    return abs(p - projection(l, p));

}

long double distanceLL(const line& l, const line& m) {

    return intersectLL(l, m) ? 0 : distanceLP(l, m.first);

}

long double distanceLS(const line& l, const line& s) {

    if (intersectLS(l, s)) return 0;

    return min(distanceLP(l, s.first), distanceLP(l, s.second));

}

long double distanceSP(const line& s, const point& p) {

    const point r = projection(s, p);

    if (intersectSP(s, r)) return abs(r - p);

    return min(abs(s.first - p), abs(s.second - p));

}

long double distanceSS(const line& s, const line& t) {

    if (intersectSS(s, t)) return 0;

    return min(min(distanceSP(s, t.first), distanceSP(s, t.second)),

               min(distanceSP(t, s.first), distanceSP(t, s.second)));

}

// a1,a2を通る直線とb1,b2を通る直線の交点計算

point intersection_l(const point& a1, const point& a2, const point& b1, const point& b2) {

    const point &a = a2 - a1, b = b2 - b1;

    return a1 + a * cross(b, b1 - a1) / cross(b, a);

}

point intersection_l(const line& l, const line& m) {

    return intersection_l(l.first, l.second, m.first, m.second);

}



//直線の単位法線ベクトルを求める

line get_unit_normalV(const point& a, const point& b) {

    line l;

    l.first = ((b - a) * point(0, 1)) / abs(b - a);

    l.second = ((b - a) * point(0, -1)) / abs(b - a);

    return l;

}



//線分sを距離dだけ平行移動

pair<line, line> get_translation(const line& s, long double d) {

    line v = get_unit_normalV(s.first, s.second);

    pair<line, line> res;

    res.first = line(s.first + v.first * d, s.second + v.first * d);

    res.second = line(s.first + v.second * d, s.second + v.second * d);

    return res;

}



struct circle {

    point o;

    long double r;

    circle() {}

    circle(const point o, const long double r) : o(o), r(r) {}

};



//2円の交差判定

int icc(const circle &c, const circle &d) {

    /*

      1 : intersect

      0 : distinct

      -1: c < d

      -2: c > d



      intersect or contain : true

      distinct             : false

    */

    long double od = abs((c.o - d.o));

    return c.r + d.r < od + eps ? 0 : od + c.r < d.r + eps ? -1 : od + d.r < c.r + eps ? -2 : 1;

}



pair<point, point> ccc(const circle &c1, const circle &c2) {

    if (!icc(c1, c2)) return pair<point, point>(c1.o, c2.o);

    long double w = abs(c2.o - c1.o), th = arg(c2.o - c1.o);

    long double dth = acosl((c1.r * c1.r + w * w - c2.r * c2.r) / (2. * c1.r * w));

    return pair<point, point>(c1.o + polar(c1.r, th - dth), c1.o + polar(c1.r, th + dth));

}



void solve() {

    //constexpr i64 mod = 1'000'000'007;

    i64 N,K;

    cin >> N >> K;



    vector<long double> x(N),y(N),c(N);

    vector<point> xy;



    rep(i,0,N){

        cin >> x[i] >> y[i] >> c[i];

        xy.emplace_back(point(x[i],y[i]));

    }



    if(K==1){

        cout << 0 << endl;

        return;

    }



    auto ok=[&](long double t){

        vector<point> os;



        rep(i,0,N){

            rep(j,i+1,N){

                const auto p=xy[i],q=xy[j];

                const long double pd=t/c[i],qd=t/c[j];

                const circle pc(p,pd),qc(q,qd);



                const auto s=icc(pc,qc);

                if(s==0) continue;

                if(s==-1){

                    os.emplace_back(p);

                    continue;

                }

                if(s==-2){

                    os.emplace_back(q);

                    continue;

                }

                const auto tmp=ccc(pc,qc);

                os.emplace_back(tmp.first);

                os.emplace_back(tmp.second);

            }

        }



        bool res=false;

        for(const auto& o:os){

            i64 cnt=0;

            rep(i,0,N){

                const auto& p=xy[i];

                const long double d=distance(o,p);

                if(is_less_or_equal(c[i]*d,t)) ++cnt;

            }

            if(cnt>=K){

                res=true;

                break;

            }

        }



        return res;

    };



    long double lb=0,ub=inf64;

    rep(loop,0,max_loop){

        long double t=(lb+ub)/2;

        if(ok(t)) ub=t;

        else lb=t;

    }



    cout << ub << endl;

}



int main() {

    std::cin.tie(0);

    std::ios::sync_with_stdio(false);

    cout.setf(ios::fixed);

    cout.precision(16);

    solve();

    return 0;

}