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 JavaScript (node.js v5.12) (judge verdict: Accepted)

function Main(input) {
    input = input.split('\n');
    input = input.map(function(e) {
        return e.split(' ').map(function(e) {
            return parseInt(e, 10);
        });
    });
    var r = 0;
    for (var i = 1; i < input.length-1; i++) {
        r += (input[i][1] - input[i][0] + 1);
    }

    console.log('%d', r);

}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));