Codeforces round #267 (Div. 2) A. George and accommodation

George has recently entered the bsucp (berland State University for cool programmers). George has a friend Alex who has also entered the university. Now they are moving into a dormitory.

George and Alex want to live in the same room. The dormitory hasNRooms in total. At the momentI-Th room hasP_{IPeople living in it and the room can accommodateQIPeople in total (PI? ≤?QI). Your task is to count how many rooms has free place for both George and Alex.}

Input

The first line contains a single integerN(1? ≤?N? ≤? 100)-the number of rooms.

TheI-Th of the nextNLines contains two integersP_{IAndQI(0? ≤?PI? ≤?QI? ≤? 100)-the number of people who already live inI-Th room and the room's capacity.}

Output

Print a single integer-the number of rooms where George and Alex can move in.

Sample test (s) Input

31 12 23 3

Output

0

Input

31 100 1010 10

Output

2. I have n dormitories, I can have a total of Qi and PI, and I can have two more dormitories. My thoughts are: directly calculate the big questions.
#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;int main() {int n;scanf("%d", &n);int p, q, ans = 0;for (int i = 0; i < n; i++) {scanf("%d%d", &q, &p);if (p - q >= 2)ans++;}printf("%d\n", ans);return 0;}

 

Codeforces round #267 (Div. 2) A. George and accommodation