P4873 [USACO14DEC] Cow Jog G

Farmer John's $N$ cows $(1

The first line of input contains $N$ and $T$. The following $N$ lines each contain the initial position and speed of a single cow. Position is a nonnegative integer and speed is a positive integer; both numbers are at most 1 billion. All cows start at distinct positions, and these will be given in increasing order in the input.

A single integer indicating the minimum number of lanes necessary so that no two cows in the same lane ever occupy the same location (including at time $T$).