B"The mayor of the Central Town wants to modernize Central Street, represented in this problem by the (Ox) axis. On this street, there are n antennas, numbered from 1 to n . The i -th antenna lies on the position x_i and has an initial scope of s_i : it covers all integer positions inside the interval [x_i - s_i; x_i + s_i] . It is possible to increment the scope of any antenna by 1 , this operation costs 1 coin. We can do this operation as much as we want (multiple times on the same antenna if we want). To modernize the street, we need to make all integer positions from 1 to m inclusive covered by at least one antenna. Note that it is authorized to cover positions outside [1; m] , even if it's not required. What is the minimum amount of coins needed to achieve this modernization? The first line contains two integers n and m ( 1 <= n <= 80 and n <= m <= 100 000 ). The i -th of the next n lines contains two integers x_i and s_i ( 1 <= x_i <= m and 0 <= s_i <= m ). On each position, there is at most one antenna (values x_i are pairwise distinct). You have to output a single integer: the minimum amount of coins required to make all integer positions from 1 to m inclusive covered by at least one antenna. In the first example, here is a possible strategy: Total cost is 40 + 210 + 31 = 281 . We can prove that it's the minimum cost required to make all positions from 1 to 595 covered by at least one antenna. Note that positions 513 and 514 are in this solution covered by two different antennas, but it's not important. -- In the second example, the first antenna already covers an interval [0; 2] so we have nothing to do. Note that the only position that we needed to cover was position 1 ; positions 0 and 2 are covered, but it's not important. "...