FZU2216

#include <iostream>
#include <string>
#include <string.h>
#include <vector>
#include <stdio.h>
#include <algorithm>
#include <map>
#include <math.h>
typedef long long LL ;

std::vector<int> stone ;
int  main(){

     int t , limit , x , n , m  , L , R , used , unUsed ;
     scanf("%d" , &t) ;
     while(t--){
          limit = 0 ;
          stone.clear() ;
          scanf("%d%d" , &n , &m) ;
          for(int i = 0 ; i < n ; i++){
               scanf("%d" , &x) ;
               if(x) stone.push_back(x) ;
               else limit++ ;
          }

          std::sort(stone.begin() , stone.end()) ;
          stone.erase( std::unique(stone.begin() , stone.end()) , stone.end() ) ;
          int res = std::min(m , limit) ;
          for(L = 0 , R = 0 ; L < stone.size() ; L++){
               while(R < stone.size() && stone[R] - stone[L] + 1 <= R - L + 1 + limit) R++ ;
               R-- ;
               used = (stone[R] - stone[L] + 1 ) - ( R - L + 1 )  ;
               unUsed = limit - used ;
               res = std::max(res ,
                                    stone[R] - stone[L] + 1
                                  + std::min(unUsed , m - (stone[R] - stone[L] + 1))) ;
         }
         std::cout<< res << std::endl ;
     }

     return 0  ;
}