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.io.DataInputStream;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.sql.RowId;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Scanner;
  import java.util.StringTokenizer;
  
  public class Main {
  
  	static class Reader {
  
  		private final int BUFFER_SIZE = 1 << 16;
  		private DataInputStream din;
  		private byte[] buffer;
  		private int bufferPointer, bytesRead;
  
  		public Reader() {
  			din = new DataInputStream(System.in);
  			buffer = new byte[BUFFER_SIZE];
  			bufferPointer = bytesRead = 0;
  		}
  
  		public Reader(String file_name) throws IOException {
  			din = new DataInputStream(new FileInputStream(file_name));
  			buffer = new byte[BUFFER_SIZE];
  			bufferPointer = bytesRead = 0;
  		}
  
  		public String readLine() throws IOException {
  			byte[] buf = new byte[64]; // line length
  			int cnt = 0, c;
  			while ((c = read()) != -1) {
  				if (c == '\n') {
  					if (cnt != 0) {
  						break;
  					} else {
  						continue;
  					}
  				}
  				buf[cnt++] = (byte) c;
  			}
  			return new String(buf, 0, cnt);
  		}
  
  		public int nextInt() throws IOException {
  			int ret = 0;
  			byte c = read();
  			while (c <= ' ') {
  				c = read();
  			}
  			boolean neg = (c == '-');
  			if (neg)
  				c = read();
  			do {
  				ret = ret * 10 + c - '0';
  			} while ((c = read()) >= '0' && c <= '9');
  
  			if (neg)
  				return -ret;
  			return ret;
  		}
  
  		public long nextLong() throws IOException {
  			long ret = 0;
  			byte c = read();
  			while (c <= ' ')
  				c = read();
  			boolean neg = (c == '-');
  			if (neg)
  				c = read();
  			do {
  				ret = ret * 10 + c - '0';
  			} while ((c = read()) >= '0' && c <= '9');
  			if (neg)
  				return -ret;
  			return ret;
  		}
  
  		public double nextDouble() throws IOException {
  			double ret = 0, div = 1;
  			byte c = read();
  			while (c <= ' ')
  				c = read();
  			boolean neg = (c == '-');
  			if (neg)
  				c = read();
  
  			do {
  				ret = ret * 10 + c - '0';
  			} while ((c = read()) >= '0' && c <= '9');
  
  			if (c == '.') {
  				while ((c = read()) >= '0' && c <= '9') {
  					ret += (c - '0') / (div *= 10);
  				}
  			}
  
  			if (neg)
  				return -ret;
  			return ret;
  		}
  
  		private void fillBuffer() throws IOException {
  			bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
  			if (bytesRead == -1)
  				buffer[0] = -1;
  		}
  
  		private byte read() throws IOException {
  			if (bufferPointer == bytesRead)
  				fillBuffer();
  			return buffer[bufferPointer++];
  		}
  
  		public void close() throws IOException {
  			if (din == null)
  				return;
  			din.close();
  		}
  	}
  
  	public static void main(String[] args) throws IOException {
  		// Reader sc = new Reader();
  		Scanner sc = new Scanner(System.in);
  		int t = sc.nextInt();
  
  		while (t-- > 0) {
  			int left = sc.nextInt();
  			int right = sc.nextInt();
  			int result = 0;
  			if (right < left * 2) {
  				result = right - left;
  			} else {
  				result = (right - 1) / 2;
  			}
  			System.out.println(result);
  		}
  
  	}
  }
  