public static void main ( String args [ ] ) {
  Scanner sc = new Scanner ( System . in ) ;
  int t = sc . nextInt ( ) ;
  for ( int i = 0 ;
  i < t ;
  i ++ ) {
    int n = sc . nextInt ( ) ;
    int [ ] a = new int [ n ] ;
    for ( int j = 0 ;
    j < n ;
    j ++ ) {
      a [ j ] = sc . nextInt ( ) ;
    }
    Arrays . sort ( a ) ;
    int k = 0 , count = 0 ;
    for ( int j = n - 1 ;
    j >= 0 ;
    j -- ) {
      if ( a [ j ] >= k + 1 ) {
        count ++ ;
      }
      k ++ ;
    }
    System . out . println ( count ) ;
  }
}

public static void main ( String args [ ] ) { Scanner sc = new Scanner ( System . in ) ; int t = sc . nextInt ( ) ; for ( int i = 0 ; i < t ; i ++ ) { int n = sc . nextInt ( ) ; int [ ] a = new int [ n ] ; for ( int j = 0 ; j < n ; j ++ ) { a [ j ] = sc . nextInt ( ) ; } Arrays . sort ( a ) ; int k = 0 , count = 0 ; for ( int j = n - 1 ; j >= 0 ; j -- ) { if ( a [ j ] >= k + 1 ) { count ++ ; } k ++ ; } System . out . println ( count ) ; } }
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