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: import java.util.*;
  import java.io.*;
  import java.math.BigInteger;
  import java.math.*;
  public class Codeforces_741_A
  {
  	static FastReader sc= new FastReader();
  	static PrintWriter out= new PrintWriter(System.out);
  	static boolean flag=false;
  	public static void main(String args[])
  	{
  		long start=System.currentTimeMillis();
  		int test=sc.nextInt();
  		while(test>0)
  		{
  			flag=false;
  			long l=sc.nextLong();
  			long r=sc.nextLong();
  		long num=r/2;
  				if(num>=l)
  					System.out.println((r-(num+1)));
  				else
  				{
  					System.out.println(r-l);
  				}
  			test--;
  		}
  		
  		
  		long end=System.currentTimeMillis();
  		//System.out.println((end-start)+" "+"m/s");
  	}
  	static long solve(long a,long b)
  	{
  		long max=0;
  		for(long i=a; i<=b; i++)
  		{
  			if((b%i)>max)
  			{
  				max=i;
  				flag=true;
  			}
  		}
  		return max;
  	}
  	
  	
  	
  	
  	
  	
  	static long gcd(long a, long b){    // GCD fun....
      		return b==0?a:gcd(b,a%b);
      }
  	static int fact(int num){           // Factorial of int...12
  		int point=1;
  		   for(int i=1; i<=num; i++)
  		   {
  			  point=point*i; 
  		   }
  		   return point;
  	}
      static BigInteger fact(BigInteger num){     // Factorial of BigInteger(>10^4)..2second
  		BigInteger one=BigInteger.valueOf(1);
  		BigInteger m=BigInteger.valueOf(1);
  		BigInteger i=one;
  		for(i=BigInteger.valueOf(1); num.compareTo(i)>=0; i=i.add(BigInteger.valueOf(1)))
  			m=m.multiply(i);
  		return m;
  	}
      static long fact(long num){                 // lfactorial of Long....(<=16)
  	    long point=1;
  		   for(long i=1; i<=num; i++)
  		   {
  			  point=point*i; 
  		   }
  		   return point;
  	}
      static void input(long arr[][],int n,int m){   //long 2d-array input...
  		for(int i=0; i<n; i++)
  		{
  			for(int j=0; j<m; j++)
  			{
  				arr[i][j]=sc.nextLong();
  			}
  		}
  	}
  	static void input(int arr[][],int n,int m){   //int 2d-array input...
  		for(int i=0; i<n; i++)
  		{
  			for(int j=0; j<m; j++)
  			{
  				arr[i][j]=sc.nextInt();
  			}
  		}
  	}
  	static void input(String arr[][],int n,int m){   //String 2d-array input...
  		for(int i=0; i<n; i++)
  		{
  			for(int j=0; j<m; j++)
  			{
  				arr[i][j]=sc.nextLine();
  			}
  		}
  	}
      static void input(long arr[],int n){            //long 1d array input
  		for(int i=0; i<n; i++)
  		{
  			arr[i]=sc.nextLong();
  		}
  	}
  	 static void input(int arr[],int n){            //int 1d array input
  		for(int i=0; i<n; i++)
  		{
  			arr[i]=sc.nextInt();
  		}
  	}
  	 static void input(char arr[],int n){            //char 1d array input
  		for(int i=0; i<n; i++)
  		{
  			arr[i]=sc.next().charAt(0);
  		}
  	}
      private static int countDigits(int l) {         //count of digit..Integer
  			if (l >= 1000000000) return 10;
  			if (l >= 100000000) return 9;
  			if (l >= 10000000) return 8;
  			if (l >= 1000000) return 7;
  			if (l >= 100000) return 6;
  			if (l >= 10000) return 5;
  			if (l >= 1000) return 4;
  			if (l >= 100) return 3;
  			if (l >= 10) return 2;
  			return 1;
  		}
      private static int countDigits(long l) {        // count of Long Digit..
  			if (l >= 1000000000000000000L) return 19;
  			if (l >= 100000000000000000L) return 18;
  			if (l >= 10000000000000000L) return 17;
  			if (l >= 1000000000000000L) return 16;
  			if (l >= 100000000000000L) return 15;
  			if (l >= 10000000000000L) return 14;
  			if (l >= 1000000000000L) return 13;
  			if (l >= 100000000000L) return 12;
  			if (l >= 10000000000L) return 11;
  			if (l >= 1000000000L) return 10;
  			if (l >= 100000000L) return 9;
  			if (l >= 10000000L) return 8;
  			if (l >= 1000000L) return 7;
  			if (l >= 100000L) return 6;
  			if (l >= 10000L) return 5;
  			if (l >= 1000L) return 4;
  			if (l >= 100L) return 3;
  			if (l >= 10L) return 2;
  			return 1;
  		}
      static class FastReader {                       // Fast input Reader class ...Jaaan
              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 s=""; 
                  try { 
                      s=br.readLine(); 
                  } 
                  catch (IOException e) { 
                      e.printStackTrace(); 
                  } 
                  return s; 
              } 			
  	}			
      static void print(long a[]) {                   //print long array
      		int n=a.length;
      		for(int i=0;i<n;i++) System.out.print(a[i]+" ");
  			System.out.println();
      	}
      static void print(int a[]) {                   //print int array
      		int n=a.length;
      		for(int i=0;i<n;i++) System.out.print(a[i]+" ");
  			System.out.println();
      	}
      static void print(String a[]) {                   //print String array
      		int n=a.length;
      		for(int i=0;i<n;i++) System.out.print(a[i]+" ");
  			System.out.println();
      	}
  	static void print(double a[]) {                   //print Double array
      		int n=a.length;
      		for(int i=0;i<n;i++) System.out.print(a[i]+" ");
  			System.out.println();
      	}
  	static void print(char a[]) {                   //print Char array
      		int n=a.length;
      		for(int i=0;i<n;i++) System.out.print(a[i]+" ");
  			System.out.println();
      	}
  }
  