Amr loves Geometry. One day he came up with a very interesting problem.

Amr has a circle of radius r and center in point (x, y). He wants the circle center to be in new position (x', y').

In one step Amr can put a pin to the border of the circle in a certain point, then rotate the circle around that pin by any angle and finally remove the pin.

Help Amr to achieve his goal in minimum number of steps.

Input

Input consists of 5 space-separated integers r, x, y, x' y' (1 ≤ r ≤ 105,  - 105 ≤ x, y, x', y' ≤ 105), circle radius, coordinates of original center of the circle and coordinates of destination center of the circle respectively.

Output

Output a single integer — minimum number of steps required to move the center of the circle to the destination point.

Examples

Input

2 0 0 0 4


Output

1


Input

1 1 1 4 4


Output

3


Input

4 5 6 5 6


Output

0

Note

In the first sample test the optimal way is to put a pin at point (0, 2) and rotate the circle by 180 degrees counter-clockwise (or clockwise, no matter).

<image>
#include <bits/stdc++.h>
using namespace std;
double tick() {
  static clock_t oldt, newt = clock();
  double diff = 1.0 * (newt - oldt) / CLOCKS_PER_SEC;
  oldt = newt;
  return diff;
}
template <typename T>
T gcd(T a, T b) {
  return (b ? __gcd(a, b) : a);
}
template <typename T>
T lcm(T a, T b) {
  return (a * (b / gcd(a, b)));
}
template <typename T>
T expo(T e, T n) {
  T x = 1, p = e;
  while (n) {
    if (n & 1) x = x * p;
    p = p * p;
    n >>= 1;
  }
  return x;
}
template <typename T>
T power(T e, T n, T m) {
  T x = 1, p = e;
  while (n) {
    if (n & 1) x = mul(x, p, m);
    p = mul(p, p, m);
    n >>= 1;
  }
  return x;
}
template <typename T>
T extended_euclid(T a, T b, T &x, T &y) {
  T xx = 0, yy = 1;
  y = 0;
  x = 1;
  while (b) {
    T q = a / b, t = b;
    b = a % b;
    a = t;
    t = xx;
    xx = x - q * xx;
    x = t;
    t = yy;
    yy = y - q * yy;
    y = t;
  }
  return a;
}
template <typename T>
T mod_inverse(T a, T n) {
  T x, y, z = 0;
  T d = extended_euclid(a, n, x, y);
  return (d > 1 ? -1 : mod_neg(x, z, n));
}
int dx[] = {0, 0, 1, -1, 1, 1, -1, -1};
int dy[] = {1, -1, 0, 0, 1, -1, 1, -1};
const int base = 1000000000;
const int base_digits = 9;
struct bigint {
  vector<int> a;
  int sign;
  int size() {
    if (a.empty()) return 0;
    int ans = (a.size() - 1) * base_digits;
    int ca = a.back();
    while (ca) ans++, ca /= 10;
    return ans;
  }
  bigint operator^(const bigint &v) {
    bigint ans = 1, a = *this, b = v;
    while (!b.isZero()) {
      if (b % 2) ans *= a;
      a *= a, b /= 2;
    }
    return ans;
  }
  string to_string() {
    stringstream ss;
    ss << *this;
    string s;
    ss >> s;
    return s;
  }
  int sumof() {
    string s = to_string();
    int ans = 0;
    for (auto c : s) ans += c - '0';
    return ans;
  }
  bigint() : sign(1) {}
  bigint(long long v) { *this = v; }
  bigint(const string &s) { read(s); }
  void operator=(const bigint &v) {
    sign = v.sign;
    a = v.a;
  }
  void operator=(long long v) {
    sign = 1;
    a.clear();
    if (v < 0) sign = -1, v = -v;
    for (; v > 0; v = v / base) a.push_back(v % base);
  }
  bigint operator+(const bigint &v) const {
    if (sign == v.sign) {
      bigint res = v;
      for (int i = 0, carry = 0; i < (int)max(a.size(), v.a.size()) || carry;
           ++i) {
        if (i == (int)res.a.size()) res.a.push_back(0);
        res.a[i] += carry + (i < (int)a.size() ? a[i] : 0);
        carry = res.a[i] >= base;
        if (carry) res.a[i] -= base;
      }
      return res;
    }
    return *this - (-v);
  }
  bigint operator-(const bigint &v) const {
    if (sign == v.sign) {
      if (abs() >= v.abs()) {
        bigint res = *this;
        for (int i = 0, carry = 0; i < (int)v.a.size() || carry; ++i) {
          res.a[i] -= carry + (i < (int)v.a.size() ? v.a[i] : 0);
          carry = res.a[i] < 0;
          if (carry) res.a[i] += base;
        }
        res.trim();
        return res;
      }
      return -(v - *this);
    }
    return *this + (-v);
  }
  void operator*=(int v) {
    if (v < 0) sign = -sign, v = -v;
    for (int i = 0, carry = 0; i < (int)a.size() || carry; ++i) {
      if (i == (int)a.size()) a.push_back(0);
      long long cur = a[i] * (long long)v + carry;
      carry = (int)(cur / base);
      a[i] = (int)(cur % base);
    }
    trim();
  }
  bigint operator*(int v) const {
    bigint res = *this;
    res *= v;
    return res;
  }
  void operator*=(long long v) {
    if (v < 0) sign = -sign, v = -v;
    for (int i = 0, carry = 0; i < (int)a.size() || carry; ++i) {
      if (i == (int)a.size()) a.push_back(0);
      long long cur = a[i] * (long long)v + carry;
      carry = (int)(cur / base);
      a[i] = (int)(cur % base);
    }
    trim();
  }
  bigint operator*(long long v) const {
    bigint res = *this;
    res *= v;
    return res;
  }
  friend pair<bigint, bigint> divmod(const bigint &a1, const bigint &b1) {
    int norm = base / (b1.a.back() + 1);
    bigint a = a1.abs() * norm;
    bigint b = b1.abs() * norm;
    bigint q, r;
    q.a.resize(a.a.size());
    for (int i = a.a.size() - 1; i >= 0; i--) {
      r *= base;
      r += a.a[i];
      int s1 = r.a.size() <= b.a.size() ? 0 : r.a[b.a.size()];
      int s2 = r.a.size() <= b.a.size() - 1 ? 0 : r.a[b.a.size() - 1];
      int d = ((long long)base * s1 + s2) / b.a.back();
      r -= b * d;
      while (r < 0) r += b, --d;
      q.a[i] = d;
    }
    q.sign = a1.sign * b1.sign;
    r.sign = a1.sign;
    q.trim();
    r.trim();
    return make_pair(q, r / norm);
  }
  bigint operator/(const bigint &v) const { return divmod(*this, v).first; }
  bigint operator%(const bigint &v) const { return divmod(*this, v).second; }
  void operator/=(int v) {
    if (v < 0) sign = -sign, v = -v;
    for (int i = (int)a.size() - 1, rem = 0; i >= 0; --i) {
      long long cur = a[i] + rem * (long long)base;
      a[i] = (int)(cur / v);
      rem = (int)(cur % v);
    }
    trim();
  }
  bigint operator/(int v) const {
    bigint res = *this;
    res /= v;
    return res;
  }
  int operator%(int v) const {
    if (v < 0) v = -v;
    int m = 0;
    for (int i = a.size() - 1; i >= 0; --i)
      m = (a[i] + m * (long long)base) % v;
    return m * sign;
  }
  void operator+=(const bigint &v) { *this = *this + v; }
  void operator-=(const bigint &v) { *this = *this - v; }
  void operator*=(const bigint &v) { *this = *this * v; }
  void operator/=(const bigint &v) { *this = *this / v; }
  bool operator<(const bigint &v) const {
    if (sign != v.sign) return sign < v.sign;
    if (a.size() != v.a.size()) return a.size() * sign < v.a.size() * v.sign;
    for (int i = a.size() - 1; i >= 0; i--)
      if (a[i] != v.a[i]) return a[i] * sign < v.a[i] * sign;
    return false;
  }
  bool operator>(const bigint &v) const { return v < *this; }
  bool operator<=(const bigint &v) const { return !(v < *this); }
  bool operator>=(const bigint &v) const { return !(*this < v); }
  bool operator==(const bigint &v) const {
    return !(*this < v) && !(v < *this);
  }
  bool operator!=(const bigint &v) const { return *this < v || v < *this; }
  void trim() {
    while (!a.empty() && !a.back()) a.pop_back();
    if (a.empty()) sign = 1;
  }
  bool isZero() const { return a.empty() || (a.size() == 1 && !a[0]); }
  bigint operator-() const {
    bigint res = *this;
    res.sign = -sign;
    return res;
  }
  bigint abs() const {
    bigint res = *this;
    res.sign *= res.sign;
    return res;
  }
  long long longValue() const {
    long long res = 0;
    for (int i = a.size() - 1; i >= 0; i--) res = res * base + a[i];
    return res * sign;
  }
  friend bigint gcd(const bigint &a, const bigint &b) {
    return b.isZero() ? a : gcd(b, a % b);
  }
  friend bigint lcm(const bigint &a, const bigint &b) {
    return a / gcd(a, b) * b;
  }
  void read(const string &s) {
    sign = 1;
    a.clear();
    int pos = 0;
    while (pos < (int)s.size() && (s[pos] == '-' || s[pos] == '+')) {
      if (s[pos] == '-') sign = -sign;
      ++pos;
    }
    for (int i = s.size() - 1; i >= pos; i -= base_digits) {
      int x = 0;
      for (int j = max(pos, i - base_digits + 1); j <= i; j++)
        x = x * 10 + s[j] - '0';
      a.push_back(x);
    }
    trim();
  }
  friend istream &operator>>(istream &stream, bigint &v) {
    string s;
    stream >> s;
    v.read(s);
    return stream;
  }
  friend ostream &operator<<(ostream &stream, const bigint &v) {
    if (v.sign == -1) stream << '-';
    stream << (v.a.empty() ? 0 : v.a.back());
    for (int i = (int)v.a.size() - 2; i >= 0; --i)
      stream << setw(base_digits) << setfill('0') << v.a[i];
    return stream;
  }
  static vector<int> convert_base(const vector<int> &a, int old_digits,
                                  int new_digits) {
    vector<long long> p(max(old_digits, new_digits) + 1);
    p[0] = 1;
    for (int i = 1; i < (int)p.size(); i++) p[i] = p[i - 1] * 10;
    vector<int> res;
    long long cur = 0;
    int cur_digits = 0;
    for (int i = 0; i < (int)a.size(); i++) {
      cur += a[i] * p[cur_digits];
      cur_digits += old_digits;
      while (cur_digits >= new_digits) {
        res.push_back(int(cur % p[new_digits]));
        cur /= p[new_digits];
        cur_digits -= new_digits;
      }
    }
    res.push_back((int)cur);
    while (!res.empty() && !res.back()) res.pop_back();
    return res;
  }
  static vector<long long> karatsubaMultiply(const vector<long long> &a,
                                             const vector<long long> &b) {
    int n = a.size();
    vector<long long> res(n + n);
    if (n <= 32) {
      for (int i = 0; i < n; i++)
        for (int j = 0; j < n; j++) res[i + j] += a[i] * b[j];
      return res;
    }
    int k = n >> 1;
    vector<long long> a1(a.begin(), a.begin() + k);
    vector<long long> a2(a.begin() + k, a.end());
    vector<long long> b1(b.begin(), b.begin() + k);
    vector<long long> b2(b.begin() + k, b.end());
    vector<long long> a1b1 = karatsubaMultiply(a1, b1);
    vector<long long> a2b2 = karatsubaMultiply(a2, b2);
    for (int i = 0; i < k; i++) a2[i] += a1[i];
    for (int i = 0; i < k; i++) b2[i] += b1[i];
    vector<long long> r = karatsubaMultiply(a2, b2);
    for (int i = 0; i < (int)a1b1.size(); i++) r[i] -= a1b1[i];
    for (int i = 0; i < (int)a2b2.size(); i++) r[i] -= a2b2[i];
    for (int i = 0; i < (int)r.size(); i++) res[i + k] += r[i];
    for (int i = 0; i < (int)a1b1.size(); i++) res[i] += a1b1[i];
    for (int i = 0; i < (int)a2b2.size(); i++) res[i + n] += a2b2[i];
    return res;
  }
  bigint operator*(const bigint &v) const {
    vector<int> a6 = convert_base(this->a, base_digits, 6);
    vector<int> b6 = convert_base(v.a, base_digits, 6);
    vector<long long> a(a6.begin(), a6.end());
    vector<long long> b(b6.begin(), b6.end());
    while (a.size() < b.size()) a.push_back(0);
    while (b.size() < a.size()) b.push_back(0);
    while (a.size() & (a.size() - 1)) a.push_back(0), b.push_back(0);
    vector<long long> c = karatsubaMultiply(a, b);
    bigint res;
    res.sign = sign * v.sign;
    for (int i = 0, carry = 0; i < (int)c.size(); i++) {
      long long cur = c[i] + carry;
      res.a.push_back((int)(cur % 1000000));
      carry = (int)(cur / 1000000);
    }
    res.a = convert_base(res.a, 6, base_digits);
    res.trim();
    return res;
  }
};
class UnionFind {
 private:
  vector<int> p, rank, setSize;
  int numSets;

 public:
  UnionFind(int N) {
    rank.assign(N, 0);
    p.assign(N, 0);
    setSize.assign(N, 1);
    for (int i = 0; i < N; i++) {
      p[i] = i;
    }
    numSets = N;
  }
  int findRank(int i) { return rank[findSet(i)]; }
  int findSet(int i) { return (p[i] == i) ? i : (p[i] = findSet(p[i])); }
  bool isSameSet(int i, int j) { return findSet(i) == findSet(j); }
  void unionSet(int i, int j) {
    if (!isSameSet(i, j)) {
      int x = findSet(i);
      int y = findSet(j);
      if (rank[x] > rank[y]) {
        p[y] = x;
        setSize[x] += setSize[y];
      } else {
        p[x] = y;
        if (rank[x] == rank[y]) rank[y]++;
        setSize[y] += setSize[x];
      }
      numSets--;
    }
  }
  int numDisjointSets() { return numSets; }
  int sizeOfSet(int i) { return setSize[findSet(i)]; }
};
class SegmentTree {
 private:
  vector<int> min_st, max_st, sum_st, A;
  int n;
  int left(int p) { return 2 * p; };
  int right(int p) { return 2 * p + 1; };
  void build(int p, int L, int R) {
    if (L == R) {
      min_st[p] = L;
      max_st[p] = L;
      sum_st[p] = A[L];
    } else {
      build(left(p), L, (L + R) / 2);
      build(right(p), (L + R) / 2 + 1, R);
      int p1 = min_st[left(p)], p2 = min_st[right(p)];
      min_st[p] = (A[p1] <= A[p2]) ? p1 : p2;
      p1 = max_st[left(p)], p2 = max_st[right(p)];
      max_st[p] = (A[p1] >= A[p2]) ? p1 : p2;
      p1 = sum_st[left(p)], p2 = sum_st[right(p)];
      sum_st[p] = p1 + p2;
    }
  }
  void update(int p, int L, int R, int index, int val) {
    if (L == R) {
      A[index] += val;
      min_st[p] = L;
      max_st[p] = L;
      sum_st[p] += val;
    } else {
      if (L <= index && index <= (L + R) / 2) {
        update(2 * p, L, (L + R) / 2, index, val);
      } else {
        update(2 * p + 1, (L + R) / 2 + 1, R, index, val);
      }
      min_st[p] = (A[min_st[left(p)]] <= A[min_st[right(p)]])
                      ? min_st[left(p)]
                      : min_st[right(p)];
      max_st[p] = (A[max_st[left(p)]] <= A[max_st[right(p)]]) ? max_st[right(p)]
                                                              : max_st[left(p)];
      sum_st[p] = sum_st[left(p)] + sum_st[right(p)];
    }
  }
  int rminq(int p, int L, int R, int i, int j) {
    if (i > R || j < L) return -1;
    if (L >= i && R <= j) return min_st[p];
    int p1 = rminq(left(p), L, (L + R) / 2, i, j);
    int p2 = rminq(right(p), (L + R) / 2 + 1, R, i, j);
    if (p1 == -1) return p2;
    if (p2 == -1) return p1;
    return (A[p1] <= A[p2]) ? p1 : p2;
  }
  int rmaxq(int p, int L, int R, int i, int j) {
    if (i > R || j < L) return -1;
    if (L >= i && R <= j) return max_st[p];
    int p1 = rmaxq(left(p), L, (L + R) / 2, i, j);
    int p2 = rmaxq(right(p), (L + R) / 2 + 1, R, i, j);
    if (p1 == -1) return p2;
    if (p2 == -1) return p1;
    return (A[p1] <= A[p2]) ? p2 : p1;
  }
  int rsq(int p, int L, int R, int i, int j) {
    if (i > R || j < L) return 0;
    if (L >= i && R <= j) return sum_st[p];
    int p1 = rsq(left(p), L, (L + R) / 2, i, j);
    int p2 = rsq(right(p), (L + R) / 2 + 1, R, i, j);
    return p1 + p2;
  }

 public:
  SegmentTree(const vector<int> &_A) {
    A = _A;
    n = A.size();
    min_st.assign(4 * n, 0);
    max_st.assign(4 * n, 0);
    sum_st.assign(4 * n, 0);
    build(1, 0, n - 1);
  }
  int rminq(int i, int j) { return rminq(1, 0, n - 1, i, j); };
  int rmaxq(int i, int j) { return rmaxq(1, 0, n - 1, i, j); };
  int rsq(int i, int j) { return rsq(1, 0, n - 1, i, j); };
  void update(int index, int val) { update(1, 0, n - 1, index, val); };
};
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  double r, x, y, x1, y1;
  cin >> r >> x >> y >> x1 >> y1;
  double a = sqrt((x - x1) * (x - x1) + (y - y1) * (y - y1));
  double d = 2 * r;
  long long int ans = ceil(a / d);
  cout << ans << endl;
  return 0;
}
