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 (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>

int main(void)
{
        int n[100][2]={0},i,num,diff[100]={0},sum=0;

        scanf("%d",&num);
        for(i=0;i<num;i++){
                scanf("%d %d",&n[i][0],&n[i][1]);
        }

        for(i=0;i<num;i++){
                diff[i] = (n[i][1]-n[i][0])+1;
        }

        for(i=0;i<num;i++){
                sum += diff[i];
        }

        printf("%d",sum);
        return 0;
}