100731: [AtCoder]ABC073 B - Theater

Memory Limit:256 MB Time Limit:2 S
Judge Style:Text Compare Creator:
Submit:0 Solved:0

Description

Score : $200$ points

Problem Statement

Joisino is working as a receptionist at a theater.

The theater has $100000$ seats, numbered from $1$ to $100000$.

According to her memo, $N$ groups of audiences have come so far, and the $i$-th group occupies the consecutive seats from Seat $l_i$ to Seat $r_i$ (inclusive).

How many people are sitting at the theater now?

Constraints

  • $1≤N≤1000$
  • $1≤l_i≤r_i≤100000$
  • No seat is occupied by more than one person.
  • All input values are integers.

Input

Input is given from Standard Input in the following format:

$N$
$l_1$ $r_1$
$:$
$l_N$ $r_N$

Output

Print the number of people sitting at the theater.


Sample Input 1

1
24 30

Sample Output 1

7

There are $7$ people, sitting at Seat $24,25,26,27,28,29$ and $30$.


Sample Input 2

2
6 8
3 3

Sample Output 2

4

Input

题意翻译

题意 你的姐姐受命要去替剧场安排座位,剧院有100000个座位,已知一共有n组人要来,每组人占据从li到ri的座位,求n组人坐好后剧场中共有多少人入座。 输入 输入1个n 然后的n+1行每行两个数,li和ri 输出 入座人数

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