Codeforces 467-A problem solution

A. George and Accommodation

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

3

1 1

2 2

3 3

output

0

input

3

1 10

0 10

10 10

output

2

Solution

• [tab]
• C++

• #include<iostream>
  using namespace std;
   
  int main()
  {
      int n,x,y,count=0;
      cin>>n;
      for(int i=1;i<=n;i++)
      {
          cin>>x>>y;
          if((y-x)>=2)
              count++;
      }
      cout<<count<<endl;
   
      return 0;
  }