Problem:
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

Solution in C# (.NET Core 3.1.201) (judge verdict: Accepted)

using System;
using System.Linq;
namespace Sample
{
  class Sample
  {
    static void Main(string[] args)
    {
    int N=int.Parse(Console.ReadLine());
      int ans=0;
      for(int i=0;i<N;i++){
       int[] arr=Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
        ans+=arr[1]-arr[0]+1;
      }
      Console.WriteLine(ans);
    }
    
  }

}