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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func main() {
	sc.Split(bufio.ScanWords)
	n := nextInt()
	l := make([]int, n)
	r := make([]int, n)
	for i := 0; i < n; i++ {
		l[i] = nextInt()
		r[i] = nextInt()
	}
	fmt.Println(n, l, r)
	res := 0
	for i := 0; i < n; i++ {
		res += r[i] - l[i] + 1
	}
	fmt.Println(res)
}

// -------- Library --------
var sc = bufio.NewScanner(os.Stdin)

func next() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	v, _ := strconv.Atoi(next())
	return v
}

func nextIntArray(size int) []int {
	res := make([]int, size)
	for i := 0; i < size; i++ {
		res[i] = nextInt()
	}
	return res
}