CF276A.Lunch Rush

Having written another programming contest, three Rabbits decided to grab some lunch. The coach gave the team exactly k time units for the lunch break.

The Rabbits have a list of n restaurants to lunch in: the i-th restaurant is characterized by two integers f__i and t__i. Value t__i shows the time the Rabbits need to lunch in the i-th restaurant. If time t__i exceeds the time k that the coach has given for the lunch break, then the Rabbits' joy from lunching in this restaurant will equal f__i - (t__i - k). Otherwise, the Rabbits get exactly f__i units of joy.

Your task is to find the value of the maximum joy the Rabbits can get from the lunch, depending on the restaurant. The Rabbits must choose exactly one restaurant to lunch in. Note that the joy value isn't necessarily a positive value.

又举办完一场编程竞赛后，三只兔子决定去吃午餐。教练恰好给了团队 $k$ 个时间单位的午休时间。

兔子们有一份包含 $n$ 家餐厅的午餐清单：第 $i$ 家餐厅由两个整数 $f_i$ 和 $t_i$ 描述。其中 $t_i$ 表示兔子在第 $i$ 家餐厅用餐所需的时间。若 $t_i$ 超过了教练所给的午休时间 $k$，则兔子在该餐厅用餐所获得的快乐值为 $f_i - (t_i - k)$；否则，兔子恰好获得 $f_i$ 单位的快乐值。

你的任务是：根据所选餐厅，求出兔子能从午餐中获得的最大快乐值。兔子必须恰好选择一家餐厅用餐。注意：快乐值不一定是正值。

The first line contains two space-separated integers — n (1 ≤ n ≤ 104) and k (1 ≤ k ≤ 109) — the number of restaurants in the Rabbits' list and the time the coach has given them to lunch, correspondingly. Each of the next n lines contains two space-separated integers — f__i (1 ≤ f__i ≤ 109) and t__i (1 ≤ t__i ≤ 109) — the characteristics of the i-th restaurant.

第一行包含两个以空格分隔的整数：$n$（$1 ≤ n ≤ 10^4$）和 $k$（$1 ≤ k ≤ 10^9$），分别表示兔子们列表中餐厅的数量以及教练给予他们的午餐时间。接下来的 $n$ 行中，每行包含两个以空格分隔的整数：$f_i$（$1 ≤ f_i ≤ 10^9$）和 $t_i$（$1 ≤ t_i ≤ 10^9$），表示第 $i$ 家餐厅的特征值。

In a single line print a single integer — the maximum joy value that the Rabbits will get from the lunch.

在一行中输出一个整数——兔子们从午餐中获得的最大快乐值。