using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
//using System.Text;
//using System.Text.RegularExpressions;
//using System.Globalization;
//using System.Diagnostics;
using static System.Console;
//using System.Numerics;
//using static System.Math;
//using pair = Pair<int, int>;

class Program
{
    static void Main()
    {
        SetOut(new StreamWriter(OpenStandardOutput()) { AutoFlush = false });
        new Program().solve();
        Out.Flush();
    }
    Scanner cin = new Scanner();
    readonly int[] dd = { 0, 1, 0, -1, 0 }; //→↓←↑
    readonly int mod = 1000000007;
    void chmax<T>(ref T a, T b) where T : IComparable<T> { a = a.CompareTo(b) < 0 ? b : a; }
    void chmin<T>(ref T a, T b) where T : IComparable<T> { a = a.CompareTo(b) < 0 ? a : b; }

    void calc()
    {
        var S = cin.next.ToCharArray();
        var T = cin.next.ToCharArray();
        int N = S.Length;

        Array.Reverse(S);
        Array.Reverse(T);

        int sr = -1;
        int tl = -1, tr = -1;
        int first = -1;
        char flag = '3';
        for (int i = 0; i < N; i++)
        {
            if (sr == -1 && S[i] == '1')
            {
                sr = i;
            }

            if (tr == -1 && T[i] == '1')
            {
                tr = i;
            }

            if (T[i] == '1')
            {
                tl = i;
            }

            if (T[i] != S[i])
            {
                first = i;
                flag = T[i];
            }
        }

        //WriteLine($"sr={sr} tl={tl} tr={tr} first={first} flag={flag}");
        if (flag == '3')
        {
            WriteLine(0);
            return;
        }
        if (flag == '1')
        {
            int cnt = 0;
            if (sr < first)
            {
                cnt = first - sr;
                cnt += first - tr;
            }
            else
            {
                cnt = sr - tr; 
            }


            WriteLine(cnt);
            return;
        }
        if (flag == '0')
        {
            int cnt = 0;

                cnt = first - sr;
                if (first > tr)
                {
                    cnt += first - tr;
                }
                else
                {
                    cnt += tr - first;
                }
            WriteLine(cnt);
            return;
        }
      


    }

    void solve()
    {
        int Q = cin.nextint;
        for (int i = 0; i < Q; i++)
        {
            calc();
        }
    }

}

class Scanner
{
    string[] s; int i;
    char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] scan { get { return ReadLine().Split(); } }
    public int[] scanint { get { return Array.ConvertAll(scan, int.Parse); } }
    public long[] scanlong { get { return Array.ConvertAll(scan, long.Parse); } }
    public double[] scandouble { get { return Array.ConvertAll(scan, double.Parse); } }
    public string next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = ReadLine();
            while (st == "") st = ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return next;
        }
    }
    public int nextint { get { return int.Parse(next); } }
    public long nextlong { get { return long.Parse(next); } }
    public double nextdouble { get { return double.Parse(next); } }
}


Measured memory_bytes: 22128