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 teenGraph
   * @Date 27 Aug 2021 01:43:41PM 
   * Noob level infinity
   * 
   * 
   * 
   * */
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Random;
  import java.util.StringTokenizer;
  import java.util.List;
  import java.util.Collections;
  import java.util.Map;
  import java.util.HashMap;
  import java.util.ArrayDeque;
  public class Junk5 {
   	private static FastScanner fs=new FastScanner();
  	// private static List<Integer> graph[];
  	private static PrintWriter out = new PrintWriter(System.out);
  	public static void main(String[] args) {		
  		int t = fs.nextInt();
  		while(t-->0)
  		{
  			int l = fs.nextInt();
  			int r = fs.nextInt();
  			int ans = (r/2)+1;
  			if(ans>=l)
  			{
  				System.out.println(r%ans);
  			}
  			else System.out.println(r-l);
  			
  		}
  
  
  	}
  	// a%b = max;
  	// 
  	
  	
  	static final Random random=new Random();
  	
  	static void ruffleSort(int [] a) {
  		int n=a.length;//shuffle, then sort 
  		for (int i=0; i<n; i++) {
  			int oi=random.nextInt(n); int temp=a[oi];
  			a[oi]=a[i]; a[i]=temp;
  		}
  		Arrays.sort(a);
  	}
  
  	
  	static class FastScanner {
  		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
  		StringTokenizer st=new StringTokenizer("");
  		String next() {
  			while (!st.hasMoreTokens())
  				try {
  					st=new StringTokenizer(br.readLine());
  				} catch (IOException e) {
  					e.printStackTrace();
  				}
  			return st.nextToken();
  		}
  		
  		int nextInt() {
  			return Integer.parseInt(next());
  		}
  		int[] readArray(int n) {
  			int[] a=new int[n];
  			for (int i=0; i<n; i++) a[i]=nextInt();
  			return a;
  		}
  		long nextLong() {
  			return Long.parseLong(next());
  		}
  		int [] sort(int [] arr)
  		{
  			List<Integer> list = new ArrayList<>();
  			for(int i : arr) list.add(i);	
  		
  			Collections.sort(list);
  			int res[] = new int[arr.length];
  			for(int i=0;i<arr.length;i++) res[i] = list.get(i);
  			
  
  			return res;
  		}
  		void debug(int a)
  		{
  			System.out.println("This is var "+a);
  		}
  	}
   
  	
  }