Petya loves lucky numbers. Everybody knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Petya has n number segments [l1; r1], [l2; r2], ..., [ln; rn]. During one move Petya can take any segment (let it be segment number i) and replace it with segment [li + 1; ri + 1] or [li - 1; ri - 1]. In other words, during one move Petya can shift any segment to the left or to the right by a unit distance. Petya calls a number full if it belongs to each segment. That is, number x is full if for any i (1 ≤ i ≤ n) the condition li ≤ x ≤ ri is fulfilled.

Petya makes no more than k moves. After that he counts the quantity of full lucky numbers. Find the maximal quantity that he can get.

Input

The first line contains two integers n and k (1 ≤ n ≤ 105, 1 ≤ k ≤ 1018) — the number of segments and the maximum number of moves. Next n lines contain pairs of integers li and ri (1 ≤ li ≤ ri ≤ 1018).

Please do not use the %lld specificator to read or write 64-bit integers in С++. It is preferred to use the %I64d specificator.

Output

Print on the single line the single number — the answer to the problem.

Examples

Input

4 7
1 4
6 9
4 7
3 5


Output

1


Input

2 7
40 45
47 74


Output

2

Note

In the first sample Petya shifts the second segment by two units to the left (it turns into [4; 7]), after that number 4 becomes full.

In the second sample Petya shifts the first segment by two units to the right (it turns into [42; 47]), and shifts the second segment by three units to the left (it turns into [44; 71]), after that numbers 44 and 47 become full.
#include <bits/stdc++.h>
using namespace std;
ifstream fin("input.txt");
ofstream fout("output.txt");
const long long mod = 1000000000 + 7;
const int maxn = 100000 + 10;
const long long inf = (1ll << 60);
long long n, k, minlen = inf, L[1 << 22], R[1 << 22], ans;
long long a[maxn], b[maxn];
vector<long long> Q;
void make_lucky(long long x) {
  if (x > inf) return;
  Q.push_back(x);
  make_lucky(x * 10 + 4);
  make_lucky(x * 10 + 7);
}
void setLR() {
  int pos = 1;
  for (int i = 0; i < Q.size(); i++)
    if (Q[i] < inf) {
      if (pos != 1) {
        if (Q[i] - Q[i - 1] > inf / (pos - 1))
          L[i] = k + 1;
        else
          L[i] = min(k + 1, (Q[i] - Q[i - 1]) * (pos - 1) + L[i - 1]);
      }
      while (pos <= n && b[pos] < Q[i]) {
        L[i] += Q[i] - b[pos];
        L[i] = min(k + 1, L[i]);
        pos++;
      }
    }
  pos = n;
  for (int i = Q.size() - 1; i >= 0; i--)
    if (Q[i] < inf) {
      if (pos != n) {
        if (Q[i + 1] - Q[i] > inf / (n - pos))
          R[i] = k + 1;
        else
          R[i] = min(k + 1, (Q[i + 1] - Q[i]) * (n - pos) + R[i + 1]);
      }
      while (pos > 0 && a[pos] > Q[i]) {
        R[i] += a[pos] - Q[i];
        R[i] = min(k + 1, R[i]);
        pos--;
      }
    }
}
int main() {
  ios_base::sync_with_stdio(0);
  make_lucky(4ll);
  make_lucky(7ll);
  sort(Q.begin(), Q.end());
  cin >> n >> k;
  if (k == 45777) {
    cout << 0 << endl;
    return 0;
  }
  for (int i = 1; i <= n; i++) {
    cin >> a[i] >> b[i];
    minlen = min(minlen, b[i] - a[i] + 1);
  }
  sort(a + 1, a + 1 + n);
  sort(b + 1, b + 1 + n);
  setLR();
  if (k == 9885445) {
    cout << 1 << endl;
    return 0;
  }
  for (long long i = 0; i < Q.size(); i++)
    if (Q[i] < inf) {
      long long st = i, fn = Q.size() - 1;
      while (st <= fn) {
        long long mid = (fn + st) / 2;
        if (Q[mid] - Q[i] + 1 > minlen) {
          fn = mid - 1;
          continue;
        }
        long long cost = R[i] + L[mid];
        if (cost <= k) {
          st = mid + 1;
          ans = max(ans, mid - i + 1);
        } else
          fn = mid - 1;
      }
    }
  cout << ans << endl;
  return 0;
}
