Problem: Petya loves lucky numbers. We all know that lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Petya and his friend Vasya play an interesting game. Petya randomly chooses an integer p from the interval [pl, pr] and Vasya chooses an integer v from the interval [vl, vr] (also randomly). Both players choose their integers equiprobably. Find the probability that the interval [min(v, p), max(v, p)] contains exactly k lucky numbers.

Input

The single line contains five integers pl, pr, vl, vr and k (1 ≤ pl ≤ pr ≤ 109, 1 ≤ vl ≤ vr ≤ 109, 1 ≤ k ≤ 1000).

Output

On the single line print the result with an absolute error of no more than 10 - 9.

Examples

Input

1 10 1 10 2


Output

0.320000000000


Input

5 6 8 10 1


Output

1.000000000000

Note

Consider that [a, b] denotes an interval of integers; this interval includes the boundaries. That is, <image>

In first case there are 32 suitable pairs: (1, 7), (1, 8), (1, 9), (1, 10), (2, 7), (2, 8), (2, 9), (2, 10), (3, 7), (3, 8), (3, 9), (3, 10), (4, 7), (4, 8), (4, 9), (4, 10), (7, 1), (7, 2), (7, 3), (7, 4), (8, 1), (8, 2), (8, 3), (8, 4), (9, 1), (9, 2), (9, 3), (9, 4), (10, 1), (10, 2), (10, 3), (10, 4). Total number of possible pairs is 10·10 = 100, so answer is 32 / 100.

In second case Petya always get number less than Vasya and the only lucky 7 is between this numbers, so there will be always 1 lucky number.

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
bool deb_mode = 0;
class debugger {
  vector<string> vars;

 public:
  template <typename T>
  debugger &operator,(const T v) {
    stringstream ss;
    ss << v, vars.push_back(ss.str());
    return *this;
  }
  void printall() {
    int j = 0, l = vars.size();
    for (int i = 0; i < (l - 1); i++) {
      if (i) cout << ", ";
      for (j; j < vars[l - 1].size(); j++) {
        if (vars[l - 1][j] == ',') {
          j++;
          break;
        }
        cout << vars[l - 1][j];
      }
      cout << " = " << vars[i];
    }
    vars.clear();
  }
} Dbug;
template <typename T1, typename T2>
inline ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
  return os << "(" << p.first << "," << p.second << ")";
}
template <typename T>
inline ostream &operator<<(ostream &os, const vector<T> &v) {
  bool first = true;
  os << "{";
  for (unsigned int i = 0; i < v.size(); i++) {
    if (!first) os << ",";
    os << v[i];
    first = false;
  }
  return os << "}";
}
template <typename T>
inline ostream &operator<<(ostream &os, const set<T> &v) {
  bool first = true;
  os << "{";
  for (typename set<T>::const_iterator ii = v.begin(); ii != v.end(); ++ii) {
    if (!first) os << ",";
    os << *ii;
    first = false;
  }
  return os << "}";
}
template <typename T1, typename T2>
inline ostream &operator<<(ostream &os, const map<T1, T2> &v) {
  bool first = true;
  os << "{";
  for (typename map<T1, T2>::const_iterator ii = v.begin(); ii != v.end();
       ++ii) {
    if (!first) os << ",";
    os << *ii;
    first = false;
  }
  return os << "}";
}
template <typename T>
void getarray(T a[], int b, int e) {
  for (int i = b; i < e + b; i++) cin >> a[i];
}
template <typename T>
void printarray(T a[], int b, int e) {
  for (int i = b; i < e - 1 + b; i++) cout << a[i] << " ";
  if (e - 1 + b >= 0) cout << a[e - 1 + b] << '\n';
}
template <typename T>
void printV(vector<T> v) {
  int sz = v.size();
  if (sz) cout << v[0];
  for (int i = 1; i < sz; i++) cout << " " << v[i];
  printf("\n");
}
template <typename T>
T gcd(T a, T b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
template <typename T>
T BigMod(T b, T p, T m) {
  if (p == 0) return 1;
  if (p % 2 == 0) {
    T s = BigMod(b, p / 2, m);
    return ((s % m) * (s % m)) % m;
  }
  return ((b % m) * (BigMod(b, p - 1, m) % m)) % m;
}
template <typename T>
T ModInv(T b, T m) {
  return BigMod(b, m - 2, m);
}
template <class T>
inline void read(T &x) {
  bool Minus = 0;
  char c;
  for (c = getchar(); c <= 32; c = getchar())
    ;
  if (c == '-') Minus = 1, c = getchar();
  for (x = 0; c > 32; c = getchar()) x = x * 10 + c - '0';
  if (Minus) x = -x;
}
char getc() {
  char c;
  for (c = getchar(); c <= 32; c = getchar())
    ;
  return c;
}
int CI(int &_x) { return scanf("%d", &_x); }
int CI(int &_x, int &_y) { return scanf("%d %d", &_x, &_y); }
int CI(int &_x, int &_y, int &_z) { return scanf("%d %d %d", &_x, &_y, &_z); }
int CI(int &_a, int &_b, int &_c, int &_d) {
  return scanf("%d %d %d %d", &_a, &_b, &_c, &_d);
}
template <class T>
string toString(T n) {
  ostringstream oss;
  oss << n;
  return oss.str();
}
int toInt(string s) {
  int r = 0;
  istringstream sin(s);
  sin >> r;
  return r;
}
long long int toLong(string s) {
  long long int r = 0;
  istringstream sin(s);
  sin >> r;
  return r;
}
bool isVowel(char ch) {
  ch = tolower(ch);
  if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u')
    return true;
  return false;
}
bool isUpper(char c) { return c >= 'A' && c <= 'Z'; }
bool isLower(char c) { return c >= 'a' && c <= 'z'; }
int dr8[8] = {+1, -1, +0, +0, +1, -1, -1, +1};
int dc8[8] = {+0, +0, -1, +1, +1, +1, -1, -1};
int dr4[4] = {+0, +0, +1, -1};
int dc4[4] = {-1, +1, +0, +0};
int kn8r[8] = {+1, +2, +2, +1, -1, -2, -2, -1};
int kn8c[8] = {+2, +1, -1, -2, -2, -1, +1, +2};
const double EPS = 1e-9;
const int INF = (1 << 30) - 1;
const long long int LINF = (1ll << 62) - 1;
const int mod = (int)1e9 + 7;
const int MAX = (int)1e5;
long long int lim = (long long int)1e9;
vector<long long int> lucky;
void dfs(long long int x) {
  if (x >= lim) return;
  lucky.push_back(x);
  dfs(x * 10 + 4);
  dfs(x * 10 + 7);
}
long long int vl, vr, pl, pr;
long long int commonLength(long long int x1, long long int x2, long long int l,
                           long long int r) {
  return max(0ll, min(x2, r) - max(x1, l) + 1);
}
long long int Calc(long long int x1, long long int x2, long long int y1,
                   long long int y2) {
  long long int ret =
      commonLength(x1, x2, pl, pr) * commonLength(y1, y2, vl, vr);
  ret += commonLength(x1, x2, vl, vr) * commonLength(y1, y2, pl, pr);
  if (x2 == y1)
    ret -= commonLength(x2, x2, pl, pr) * commonLength(y1, y1, vl, vr);
  return ret;
}
int main() {
  if (deb_mode) srand(int(time(NULL)));
  int i, j, k, l, n, m, q, a, b, c;
  dfs(0ll);
  lucky.push_back(lim);
  sort(lucky.begin(), lucky.end());
  cin >> pl >> pr >> vl >> vr >> k;
  long long int allSpace = (pr - pl + 1ll) * (vr - vl + 1ll);
  long long int posSpace = 0ll;
  for (i = 1; i + k < lucky.size(); i++) {
    posSpace +=
        Calc(lucky[i - 1] + 1, lucky[i], lucky[i + k - 1], lucky[i + k] - 1);
  }
  if (deb_mode) {
    cout << "Line= " << 257 << " -> ";
    Dbug, posSpace, allSpace, "posSpace, allSpace";
    Dbug.printall();
    cout << '\n';
  };
  cout << fixed << setprecision(12) << (long double)posSpace / allSpace << "\n";
  if (deb_mode) cerr << "TIME = " << clock() << " ms" << '\n';
  return 0;
}