#include <bits/stdc++.h>
#pragma GCC target("avx2")
#pragma GCC optimization("O3")
#pragma GCC optimization("unroll-loops")
using namespace std;
template <class T>
using vec = std::vector<T>;
template <class T>
using vec2d = std::vector<std::vector<T>>;
template <class T>
vec2d<T> makeVec2d(const int n1, const int n2) {
  return vec2d<T>(n1, vec<T>(n2));
}
bool __hack = std::ios::sync_with_stdio(false);
auto __hack1 = cin.tie(nullptr);
struct Input {
  Input(istream& in) : in(&in) {}
  template <class T>
  T next() const {
    T x;
    *in >> x;
    return x;
  }
  int ni() const { return next<int>(); }
  istream* in;
};
Input in(cin);
class Output {
 private:
  ostream* out;
  template <typename T>
  void printSingle(const T& value) {
    *out << value;
  }

 public:
  Output(ostream& out) : out(&out) {}
  inline void setPrecision(int d) { *out << fixed << setprecision(d); }
  inline void print() {}
  template <typename T, typename... Ts>
  inline void print(const T& f, const Ts&... args) {
    printSingle(f);
    if (sizeof...(args) != 0) {
      *out << ' ';
      print(args...);
    }
  }
  template <typename... Ts>
  inline void println(const Ts&... args) {
    print(args...);
    *out << '\n';
  }
  template <typename... Ts>
  inline void operator()(const Ts&... args) {
    println(args...);
  }
};
Output out(cout);
namespace template_util {
constexpr int bytecount(uint64_t x) { return x ? 1 + bytecount(x >> 8) : 0; }
template <int N>
struct bytetype {};
template <uint64_t N>
struct minimal_uint : bytetype<bytecount(N)> {};
}  // namespace template_util
double PI = acos(-1.);
template <class T>
struct Point {
  T x, y;
  Point(const T& x, const T& y) : x(x), y(y) {}
};
template <class T1, class T2>
inline auto operator*(const Point<T1>& p1, const Point<T2>& p2)
    -> decltype(p1.x * p2.x + p1.y * p2.y) {
  return p1.x * p2.x + p1.y * p2.y;
}
template <class T>
inline auto angle(const Point<T>& point) -> decltype(atan2(point.y, point.x)) {
  return atan2(point.y, point.x);
}
template <class T>
inline auto length(const Point<T>& point) -> decltype(sqrt(point * point)) {
  return sqrt(point * point);
}
void solve(istream& inStream, ostream& outStream) {
  in = Input(inStream);
  out = Output(outStream);
  auto n = in.ni();
  auto m = in.ni();
  vec<pair<double, double>> ps(n);
  auto nrm = [](pair<double, double> x) -> pair<double, double> {
    while (x.first < 0) {
      x.first += 2 * PI;
      x.second += 2 * PI;
    }
    while (x.first >= 2 * PI) {
      x.first -= 2 * PI;
      x.second -= 2 * PI;
    }
    return x;
  };
  auto check = [&](double d) -> bool {
    vec<pair<double, double>> segs;
    for (int i = 0; i < (n); ++i) {
      double offset = acos(min(d / ps[i].second, 1.0));
      segs.push_back(
          nrm(make_pair(ps[i].first - offset, ps[i].first + offset)));
    }
    sort(segs.begin(), segs.end());
    vec<pair<double, double>> segs2;
    for (auto s : segs) {
      while (!segs2.empty() && segs2.back().second >= s.second)
        segs2.pop_back();
      segs2.push_back(s);
    }
    double limit = segs2.front().second + 2 * PI;
    while (segs2.back().second >= limit) {
      segs2.pop_back();
    }
    segs = segs2;
    int sz = segs.size();
    for (int i = 0; i < (sz); ++i) {
      segs.push_back({segs[i].first + 2 * PI, segs[i].second + 2 * PI});
    }
    int idx = 2 * sz;
    vec2d<int> nxt = makeVec2d<int>(2 * sz + 1, 17);
    for (int j = 0; j < (17); ++j) nxt[idx][j] = idx;
    for (int i = 2 * sz - 1; i >= 0; --i) {
      while (segs[idx - 1].first > segs[i].second) {
        --idx;
      }
      nxt[i][0] = idx;
    }
    for (int j = (1); j < (17); ++j)
      for (int i = 0; i < (2 * sz); ++i) nxt[i][j] = nxt[nxt[i][j - 1]][j - 1];
    for (int i = 0; i < (sz); ++i) {
      int res = 0;
      int cur = i;
      for (int j = 16; j >= 0; --j) {
        if (nxt[cur][j] < i + sz) {
          res += (1 << j);
          cur = nxt[cur][j];
        }
      }
      if (res + 1 <= m) return true;
    }
    return false;
  };
  double r = 1e100;
  for (int i = 0; i < (n); ++i) {
    auto x = in.next<double>();
    auto y = in.next<double>();
    auto p = Point<double>(x, y);
    ps[i] = {angle(p), length(p)};
    r = min(r, ps[i].second);
  }
  out.setPrecision(15);
  if (m >= n) {
    out(r);
    return;
  }
  double l = 0;
  for (int iter = 0; iter < (70); ++iter) {
    double e = (l + r) / 2;
    if (check(e)) {
      l = e;
    } else {
      r = e;
    }
  }
  out((l + r) / 2);
}
int main() {
  solve(cin, cout);
  return 0;
}
