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문제

Farmer John has returned to the County Fair so he can attend the special events (concerts, rodeos, cooking shows, etc.). He wants to attend as many of the N (1 <= N <= 10,000) special events as he possibly can.

He's rented a bicycle so he can speed from one event to the next in absolutely no time at all (0 time units to go from one event to the next!).

Given a list of the events that FJ might wish to attend, with their start times (1 <= T <= 100,000) and their durations (1 <= L <= 100,000), determine the maximum number of events that FJ can attend. FJ never leaves an event early.

입력

  • Line 1: A single integer, N.
  • Lines 2..N+1: Each line contains two space-separated integers, T and L, that describe an event that FJ might attend.

출력

  • Line 1: A single integer that is the maximum number of events FJ can attend.

예제 입력 1

7
1 6
8 6
14 5
19 2
1 8
18 3
10 6

예제 출력 1

4