public static void main ( String [ ] args ) {
  FastScanner fs = new FastScanner ( ) ;
  int t = fs . nextInt ( ) ;
  while ( t -- > 0 ) {
    int n = fs . nextInt ( ) ;
    ArrayList < Integer > a = new ArrayList < > ( ) ;
    for ( int i = 0 ;
    i < n ;
    i ++ ) {
      int b = fs . nextInt ( ) ;
      a . add ( b ) ;
    }
    Collections . sort ( a ) ;
    int ans = 0 ;
    int prev = 0 ;
    if ( n > 0 ) prev = a . get ( 0 ) ;
    for ( int i : a ) {
      if ( prev + 1 == i ) {
        ans ++ ;
      }
      prev = i ;
    }
    if ( ans > 0 ) {
      ans = 2 ;
    }
    else ans = 1 ;
    System . out . println ( ans ) ;
  }
}

public static void main ( String [ ] args ) { FastScanner fs = new FastScanner ( ) ; int t = fs . nextInt ( ) ; while ( t -- > 0 ) { int n = fs . nextInt ( ) ; ArrayList < Integer > a = new ArrayList < > ( ) ; for ( int i = 0 ; i < n ; i ++ ) { int b = fs . nextInt ( ) ; a . add ( b ) ; } Collections . sort ( a ) ; int ans = 0 ; int prev = 0 ; if ( n > 0 ) prev = a . get ( 0 ) ; for ( int i : a ) { if ( prev + 1 == i ) { ans ++ ; } prev = i ; } if ( ans > 0 ) { ans = 2 ; } else ans = 1 ; System . out . println ( ans ) ; } }
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