|Codeforces Round #177 (Div. 2)|
Little penguin Polo adores integer segments, that is, pairs of integers [l; r] (l ≤ r).
He has a set that consists of n integer segments: [l 1; r 1], [l 2; r 2], ..., [l n; r n]. We know that no two segments of this set intersect. In one move Polo can either widen any segment of the set 1 unit to the left or 1 unit to the right, that is transform [l; r] to either segment [l - 1; r], or to segment [l; r + 1].
The value of a set of segments that consists of n segments [l 1; r 1], [l 2; r 2], ..., [l n; r n] is the number of integers x, such that there is integer j, for which the following inequality holds, l j ≤ x ≤ r j.
Find the minimum number of moves needed to make the value of the set of Polo's segments divisible by k.
The first line contains two integers n and k (1 ≤ n, k ≤ 105). Each of the following n lines contain a segment as a pair of integers l i and r i ( - 105 ≤ l i ≤ r i ≤ 105), separated by a space.
It is guaranteed that no two segments intersect. In other words, for any two integers i, j (1 ≤ i < j ≤ n) the following inequality holds, min(r i, r j) < max(l i, l j).
In a single line print a single integer — the answer to the problem.