description: You are given two integers l and r, l≤ r. Find the largest possible value of a mod b over all pairs (a, b) of integers for which r≥ a ≥ b ≥ l.
  
  As a reminder, a mod b is a remainder we get when dividing a by b. For example, 26 mod 8 = 2.
  
  Input
  
  Each test contains multiple test cases.
  
  The first line contains one positive integer t (1≤ t≤ 10^4), denoting the number of test cases. Description of the test cases follows.
  
  The only line of each test case contains two integers l, r (1≤ l ≤ r ≤ 10^9).
  
  Output
  
  For every test case, output the largest possible value of a mod b over all pairs (a, b) of integers for which r≥ a ≥ b ≥ l.
  
  Example
  
  Input
  
  
  4
  1 1
  999999999 1000000000
  8 26
  1 999999999
  
  
  Output
  
  
  0
  1
  12
  499999999
  
  Note
  
  In the first test case, the only allowed pair is (a, b) = (1, 1), for which a mod b = 1 mod 1 = 0.
  
  In the second test case, the optimal choice is pair (a, b) = (1000000000, 999999999), for which a mod b = 1.
solution: // Author: FarazAhmad
  import java.util.*;
  import java.io.*;
  import java.math.*;
  public class Fa {
  	static class FastReader {
  		BufferedReader br;
  		StringTokenizer st;
  
  		public FastReader()
  		{
  			br = new BufferedReader(
  				new InputStreamReader(System.in));
  		}
  
  		String next()
  		{
  			while (st == null || !st.hasMoreElements()) {
  				try {
  					st = new StringTokenizer(br.readLine());
  				}
  				catch (IOException e) {
  					e.printStackTrace();
  				}
  			}
  			return st.nextToken();
  		}
  
  		int nextInt() { return Integer.parseInt(next()); }
  
  		long nextLong() { return Long.parseLong(next()); }
  
  		double nextDouble()
  		{
  			return Double.parseDouble(next());
  		}
  
  		String nextLine()
  		{
  			String str = "";
  			try {
  				str = br.readLine();
  			}
  			catch (IOException e) {
  				e.printStackTrace();
  			}
  			return str;
  		}
  	}
  	static void swap(int []list,int i){
  		int temp;
  		temp=list[i];
  		list[i]=list[i+1];
  		list[i+1]=temp;
  		return;
  	}
  static void decimal_places(double n){
  	System.out.format("%.9f", n);
  	System.out.println();
  }
  static void helper(char[] arr, int i, int prev){
  	for(int j=i-1;j>=0;j--){
  	  if(prev=='B'){
  		arr[j]='R';
  		prev='R';
  	  }
  	  else{
  		arr[j]='B';
  		prev='B';
  	  }
  	}
    }
    
  	public static void main(String[] args)
  	{
  		FastReader sc = new FastReader();
  		int t=sc.nextInt();
  	// Vector<String> powers=new Vector<>();
  	// BigInteger in =  new BigInteger("1000000000000000000");
  	// 	   BigInteger ind =  new BigInteger("1");  
  	// 	   BigInteger ii =  new BigInteger("2");  
  
  	// 		while(ind.compareTo(in)==-1||ind.compareTo(in)==0)
  	// 		{
  	// 			powers.add(""+ind);
  	// 			ind =ind.multiply(ii);
  	// 		}
  		//first:
          for(int tt=0;tt<t;tt++){ 
  			long l=sc.nextLong();
  			long r=sc.nextLong();
  			if((r/2+1)>=l) System.out.println(r%(r/2+1));
  			else System.out.println(r-l);
  			
  
  }
  }
  }
  
  