CodeForces

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

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 pi people living in it and the room can accommodate qi people 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 integer n (1 ≤ n ≤ 100) — the number of rooms.

The i-th of the next n lines contains two integers pi and qi (0 ≤ pi ≤ qi ≤ 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.

Examples

input

31 12 23 3

output

0

input

31 100 1010 10

output

2

题意：George跟Alex想住在同一个房间，统计所有房间内剩下的床位大于等于2个的

代码：

#include<cstdio>int main() {int n,ans=0;scanf("%d",&n);for(int i=1;i<=n;i++){int a,b;scanf("%d%d",&a,&b);if(b-a>=2){ans++;}}printf("%d",ans);return 0;}