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 has n rooms in total. At the moment the i-th room has p_i people living in it and the room can accommodate q_i people in total (p_i ≤ q_i). Your task is to count how many rooms has free place for both George and Alex.

Input

The first line contains a single integer n (1 ≤ n ≤ 100) — the number of rooms.

The i-th of the next n lines contains two integers p_i and q_i (0 ≤ p_i ≤ q_i ≤ 100) — the number of people who already live in the i-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

3
1 1
2 2
3 3

Output

0

Input

3
1 10
0 10
10 10

Output

2
题意：有n个寝室，一共可以住qi,已经住了pi个，问再来两个可以住进去几个寝室
思路：直接计算的大水题
#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;
}