프로그램 명: coci_kruznice
제한시간: 1 초
[요약]
X축 위에 놓여진 원들의 X좌표와 반지름이 주어졌을 때 전체 평면이 총 몇 개의 면으로 나뉘는지 출력하세요.
어떤 원도 서로 교차하지 않는다
Enjoying a casual afternoon walk in the coordinate system, little Luka has encountered N unique
circles with its centers lying on the x-axis. The circles do not intersect, but they can touch (from the
inside and the outside). Fascinated with circles, Luka wondered how many regions the circles divide
the plane into. Of course, you are going to help him answer this question.
A region is a set of points such that each two points can be connected with a continuous curve,
without cutting through any of the circles.
INPUT
-
The first line of input contains the integer N (1 ≤ N ≤ 300 000), the number of circles.
-
Each of the following N lines contains two integers xi and ri (-10^9 ≤ xi ≤ 10^9 , 1 ≤ ri ≤ 10^9), the number xi representing the x coordinate of the i th circle and the number ri representing the radius of the i th circle.
All the circles in the input will be unique.
OUTPUT
The first and only line of output must contain the required number from the task.
SAMPLE TESTS
input
2
1 3
5 1
output
3
input
3
2 2
1 1
3 1
output
5
input
4
7 5
-9 11
11 9
0 20
output
6
Clarification of the third example: The example corresponds to the image in the task statement.
출처:coci/2013-2014/contest6 4 번
요약:ladown21
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