description: A binary string is a string that consists of characters 0 and 1. A bi-table is a table that has exactly two rows of equal length, each being a binary string.
  
  Let \operatorname{MEX} of a bi-table be the smallest digit among 0, 1, or 2 that does not occur in the bi-table. For example, \operatorname{MEX} for \begin{bmatrix} 0011\\\ 1010 \end{bmatrix} is 2, because 0 and 1 occur in the bi-table at least once. \operatorname{MEX} for \begin{bmatrix} 111\\\ 111 \end{bmatrix} is 0, because 0 and 2 do not occur in the bi-table, and 0 < 2.
  
  You are given a bi-table with n columns. You should cut it into any number of bi-tables (each consisting of consecutive columns) so that each column is in exactly one bi-table. It is possible to cut the bi-table into a single bi-table — the whole bi-table.
  
  What is the maximal sum of \operatorname{MEX} of all resulting bi-tables can be?
  
  Input
  
  The input consists of multiple test cases. The first line contains a single integer t (1 ≤ t ≤ 10^4) — the number of test cases. Description of the test cases follows.
  
  The first line of the description of each test case contains a single integer n (1 ≤ n ≤ 10^5) — the number of columns in the bi-table.
  
  Each of the next two lines contains a binary string of length n — the rows of the bi-table.
  
  It's guaranteed that the sum of n over all test cases does not exceed 10^5.
  
  Output
  
  For each test case print a single integer — the maximal sum of \operatorname{MEX} of all bi-tables that it is possible to get by cutting the given bi-table optimally.
  
  Example
  
  Input
  
  
  4
  7
  0101000
  1101100
  5
  01100
  10101
  2
  01
  01
  6
  000000
  111111
  
  
  Output
  
  
  8
  8
  2
  12
  
  Note
  
  In the first test case you can cut the bi-table as follows:
  
    * \begin{bmatrix} 0\\\ 1 \end{bmatrix}, its \operatorname{MEX} is 2.
    * \begin{bmatrix} 10\\\ 10 \end{bmatrix}, its \operatorname{MEX} is 2.
    * \begin{bmatrix} 1\\\ 1 \end{bmatrix}, its \operatorname{MEX} is 0.
    * \begin{bmatrix} 0\\\ 1 \end{bmatrix}, its \operatorname{MEX} is 2.
    * \begin{bmatrix} 0\\\ 0 \end{bmatrix}, its \operatorname{MEX} is 1.
    * \begin{bmatrix} 0\\\ 0 \end{bmatrix}, its \operatorname{MEX} is 1.
  
  
  
  The sum of \operatorname{MEX} is 8.
solution: 
  import java.io.*;
  import java.util.*;
  import java.util.function.BiFunction;
  
  public class C {
      static FastReader reader = new FastReader();
      static OutputWriter out = new OutputWriter(System.out);
  
      static int go(int i, int[][] arr, int[] dp) {
          if (i >= arr[0].length) return 0;
          if (dp[i] != -1) return dp[i];
  
          int max = 0;
          if (arr[0][i] != 0 && arr[1][i] != 0) {
              max = go(i + 1, arr, dp);
          } else if(arr[0][i] != 1 && arr[1][i] != 1) {
              max = go(i + 1, arr, dp) + 1;
          } else {
              max = go(i + 1, arr, dp) + 2;
          }
  
          if (i + 1 < arr[0].length) {
              int zeros = 0;
              int ones = 0;
              for (int r = 0; r < 2; r++) {
                  for (int col = i; col <= i + 1; col++) {
                      if (arr[r][col] == 1) {
                          ones++;
                      } else {
                          zeros++;
                      }
                  }
                  if (zeros > 0 && ones > 0) {
                      max = Math.max(go(i + 2, arr, dp) + 2, max);
                  } else if (zeros > 0) {
                      max = Math.max(go(i + 2, arr, dp) + 1, max);
                  } else {
                      max = Math.max(go(i + 2, arr, dp), max);
                  }
              }
          }
          dp[i] = max;
          return dp[i];
      }
      public static void main(String[] args) {
          int tests = reader.nextInt();
          for (int test = 1; test <= tests; test++) {
              int n = reader.nextInt();
              int[][] arr = new int[2][n];
              for (int i = 0; i < 2; i++) {
                  char[] str = reader.next().toCharArray();
                  for (int j = 0; j < n; j++) {
                      arr[i][j] = str[j] - '0';
                  }
              }
  
              int[] dp = new int[n];
              Arrays.fill(dp, -1);
              out.println(go(0, arr, dp));
          }
          out.flush();
      }
  
      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;
          }
      }
  
      public static class OutputWriter {
          private final PrintWriter writer;
  
          public OutputWriter(OutputStream outputStream) {
              writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
          }
  
          public OutputWriter(Writer writer) {
              this.writer = new PrintWriter(writer);
          }
  
          public void print(char[] array) {
              writer.print(array);
          }
  
          public void print(Object... objects) {
              for (int i = 0; i < objects.length; i++) {
                  if (i != 0) {
                      writer.print(' ');
                  }
                  writer.print(objects[i]);
              }
          }
  
          public void print(int[] array) {
              for (int i = 0; i < array.length; i++) {
                  if (i != 0) {
                      writer.print(' ');
                  }
                  writer.print(array[i]);
              }
          }
  
          public void print(double[] array) {
              for (int i = 0; i < array.length; i++) {
                  if (i != 0) {
                      writer.print(' ');
                  }
                  writer.print(array[i]);
              }
          }
  
          public void print(long[] array) {
              for (int i = 0; i < array.length; i++) {
                  if (i != 0) {
                      writer.print(' ');
                  }
                  writer.print(array[i]);
              }
          }
  
          public void println(int[] array) {
              print(array);
              writer.println();
          }
  
          public void println(double[] array) {
              print(array);
              writer.println();
          }
  
          public void println(long[] array) {
              print(array);
              writer.println();
          }
  
          public void println() {
              writer.println();
          }
  
          public void println(Object... objects) {
              print(objects);
              writer.println();
          }
  
          public void print(char i) {
              writer.print(i);
          }
  
          public void println(char i) {
              writer.println(i);
          }
  
          public void println(char[] array) {
              writer.println(array);
          }
  
          public void printf(String format, Object... objects) {
              writer.printf(format, objects);
          }
  
          public void close() {
              writer.close();
          }
  
          public void flush() {
              writer.flush();
          }
  
          public void print(long i) {
              writer.print(i);
          }
  
          public void println(long i) {
              writer.println(i);
          }
  
          public void print(int i) {
              writer.print(i);
          }
  
          public void println(int i) {
              writer.println(i);
          }
  
          public void separateLines(int[] array) {
              for (int i : array) {
                  println(i);
              }
          }
      }
  }
  