4053: Lucky Segments
Description
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.
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 C++. It is preferred to use the %I64d specificator.
Print on the single line the single number − the answer to the problem.
4 7
1 4
6 9
4 7
3 5
1
2 7
40 45
47 74
2
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.