A8343. Lucky Segments

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 $[l_{1}; r_{1}]$ , $[l_{2}; r_{2}]$ , ..., $[l_{n}; r_{n}]$ . During one move Petya can take any segment (let it be segment number $i$ ) and replace it with segment $[l_{i}+1; r_{i}+1]$ or $[l_{i}-1; r_{i}-1]$ . 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 $l_{i}<=x<=r_{i}$ 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.

The first line contains two integers $n$ and $k$ ( $1<=n<=10^{5}$ , $1<=k<=10^{18})$ — the number of segments and the maximum number of moves. Next $n$ lines contain pairs of integers $l_{i}$ and $r_{i}$ $(1<=l_{i}<=r_{i}<=10^{18})$ .

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

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

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.