Codeforces Round #232 (Div. 2), problem: (A) On Segment's Own Points solution

Codeforces Round #232 (Div. 2), problem: (A) On Segment's Own Points: http://codeforces.ru/contest/397/problem/A

Codeforces Round #232 (Div. 2), problem: (A) On Segment's Own Points solution: http://ideone.com/WJ0C5y

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

int main() {
    int n, l, r, a, b, arr[110], cnt, flag;
    scanf("%d", &n);
    scanf("%d%d", &a, &b);
    cnt=flag=0;
    memset(arr, 0, sizeof(arr));
    for(int i=a; i<b; i++) arr[i]++;
    for(int i=1; i<n; i++) {
        scanf("%d%d", &l, &r);
        for(int j=l; j<r; j++) arr[j]++;
    }
    for(int i=a; i<b; i++) {
        if(arr[i]==1) cnt++;
    }
    printf("%d\n", cnt);
    return 0;
}