CodeForces 1293A

import java.util.*;
public class sol{
    static int n, s, k;
    static int[] floors;
    public static void main(String[] args){
        Scanner console = new Scanner(System.in);
        int t = console.nextInt();
        for ( int i = 0; i < t; t++ )
        {
            n = console.nextInt();
            s = console.nextInt();
            k = console.nextInt();
            floors = new int[n+1];
            for ( int j = 0; j < k; j++ )
            {
                floors[console.nextInt()] = -1;
            }
            System.out.println(function(0,n-1,floors,s)-s);
        }
    }
    static int function ( int l , int r , int[] arr, int x )
    {
        int ans = -1;
        while ( l <= r )
        {
            int mid = l + ( r - l ) / 2;
            if ( mid >= x && arr[mid] != -1)
            {
                ans = mid;
            }
            else
            {
                l = mid + 1;
            }
        }
        return ans;
    }
}