description: YouKn0wWho has two even integers x and y. Help him to find an integer n such that 1 ≤ n ≤ 2 ⋅ 10^{18} and n mod x = y mod n. Here, a mod b denotes the remainder of a after division by b. If there are multiple such integers, output any. It can be shown that such an integer always exists under the given constraints.
  
  Input
  
  The first line contains a single integer t (1 ≤ t ≤ 10^5) — the number of test cases.
  
  The first and only line of each test case contains two integers x and y (2 ≤ x, y ≤ 10^9, both are even).
  
  Output
  
  For each test case, print a single integer n (1 ≤ n ≤ 2 ⋅ 10^{18}) that satisfies the condition mentioned in the statement. If there are multiple such integers, output any. It can be shown that such an integer always exists under the given constraints.
  
  Example
  
  Input
  
  
  4
  4 8
  4 2
  420 420
  69420 42068
  
  
  Output
  
  
  4
  10
  420
  9969128
  
  Note
  
  In the first test case, 4 mod 4 = 8 mod 4 = 0.
  
  In the second test case, 10 mod 4 = 2 mod 10 = 2.
  
  In the third test case, 420 mod 420 = 420 mod 420 = 0.
solution: //package Codeforces.Round752Div2;
  
  import java.io.*;
  import java.util.*;
  
  public class D {
      static long solve(long x, long y){
          long max = (y/x) * x;
          return (max + y)/2;
      }
      public static void main(String[] args) throws IOException {
          /*long start = System.currentTimeMillis();
          Soumit sc = new Soumit("Input.txt");*/
  
          Soumit sc = new Soumit();
  
          int t = sc.nextInt();
          StringBuilder sb = new StringBuilder();
          while (t-->0){
              long x = sc.nextLong();
              long y = sc.nextLong();
  
              if(x==y){
                  sb.append(x).append("\n");
              }
              else if(x%y==0){
                  sb.append(x+y).append("\n");
              }
              else if(y%x==0){
                  sb.append(x).append("\n");
              }
              else if(x>y){
                  sb.append(x+y).append("\n");
              }
              else{
                  long ans = solve(x, y);
                  sb.append(ans).append("\n");
              }
          }
  
          System.out.println(sb);
  
          /*long end = System.currentTimeMillis();
          System.out.println(((double) end-start)/1000.0);*/
  
          sc.close();
      }
  
      static class Soumit {
          final private int BUFFER_SIZE = 1 << 18;
          final private DataInputStream din;
          final private byte[] buffer;
          private PrintWriter pw;
          private int bufferPointer, bytesRead;
          StringTokenizer st;
  
          public Soumit() {
              din = new DataInputStream(System.in);
              buffer = new byte[BUFFER_SIZE];
              bufferPointer = bytesRead = 0;
          }
  
          public Soumit(String file_name) throws IOException {
              din = new DataInputStream(new FileInputStream(file_name));
              buffer = new byte[BUFFER_SIZE];
              bufferPointer = bytesRead = 0;
          }
  
          public void streamOutput(String file) throws IOException {
              FileWriter fw = new FileWriter(file);
              BufferedWriter bw = new BufferedWriter(fw);
              pw = new PrintWriter(bw);
          }
  
          public void println(String a) {
              pw.println(a);
          }
  
          public void print(String a) {
              pw.print(a);
          }
  
          public String readLine() throws IOException {
              byte[] buf = new byte[3000064]; // line length
              int cnt = 0, c;
              while ((c = read()) != -1) {
                  if (c == '\n')
                      break;
                  buf[cnt++] = (byte) c;
              }
              return new String(buf, 0, cnt);
          }
  
          String next() {
              while (st == null || !st.hasMoreElements()) {
                  try {
                      st = new StringTokenizer(readLine());
                  } catch (IOException e) {
                      e.printStackTrace();
                  }
              }
              return st.nextToken();
          }
  
          public void sort(int[] arr) {
              ArrayList<Integer> arlist = new ArrayList<>();
              for (int i : arr)
                  arlist.add(i);
  
              Collections.sort(arlist);
              for (int i = 0; i < arr.length; i++)
                  arr[i] = arlist.get(i);
          }
  
          public void sort(long[] arr) {
              ArrayList<Long> arlist = new ArrayList<>();
              for (long i : arr)
                  arlist.add(i);
  
              Collections.sort(arlist);
              for (int i = 0; i < arr.length; i++)
                  arr[i] = arlist.get(i);
          }
  
          public int[] nextIntArray(int n) throws IOException {
              int[] arr = new int[n];
              for (int i = 0; i < n; i++) {
                  arr[i] = nextInt();
              }
  
              return arr;
          }
  
          public long[] nextLongArray(int n) throws IOException {
              long[] arr = new long[n];
              for (int i = 0; i < n; i++) {
                  arr[i] = nextLong();
              }
  
              return arr;
          }
  
          public double[] nextDoubleArray(int n) throws IOException {
              double[] arr = new double[n];
              for (int i = 0; i < n; i++) {
                  arr[i] = nextDouble();
              }
  
              return arr;
          }
  
          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;*/
              if (din != null) din.close();
              if (pw != null) pw.close();
          }
      }
  }
  