public static void main ( String [ ] args ) {
  Scanner in = new Scanner ( System . in ) ;
  int n = in . nextInt ( ) ;
  int m = in . nextInt ( ) ;
  int min = Integer . MAX_VALUE ;
  for ( int i = 0 ;
  i < m ;
  i ++ ) {
    int j = in . nextInt ( ) ;
    int k = in . nextInt ( ) ;
    int ans = k - j + 1 ;
    if ( ans < min ) min = ans ;
  }
  System . out . println ( min ) ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    System . out . print ( ( i % min ) + " " ) ;
  }
}

public static void main ( String [ ] args ) { Scanner in = new Scanner ( System . in ) ; int n = in . nextInt ( ) ; int m = in . nextInt ( ) ; int min = Integer . MAX_VALUE ; for ( int i = 0 ; i < m ; i ++ ) { int j = in . nextInt ( ) ; int k = in . nextInt ( ) ; int ans = k - j + 1 ; if ( ans < min ) min = ans ; } System . out . println ( min ) ; for ( int i = 0 ; i < n ; i ++ ) { System . out . print ( ( i % min ) + " ▁ " ) ; } }
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