public static void main ( String [ ] args ) {
  Scanner scan = new Scanner ( System . in ) ;
  int n = scan . nextInt ( ) ;
  int s = scan . nextInt ( ) ;
  int [ ] [ ] floor = new int [ n ] [ 2 ] ;
  int t = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    floor [ i ] [ 0 ] = scan . nextInt ( ) ;
    floor [ i ] [ 1 ] = scan . nextInt ( ) ;
  }
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    for ( int j = i + 1 ;
    j < n ;
    j ++ ) {
      if ( floor [ i ] [ 0 ] < floor [ j ] [ 0 ] ) {
        int x = floor [ i ] [ 0 ] ;
        floor [ i ] [ 0 ] = floor [ j ] [ 0 ] ;
        floor [ j ] [ 0 ] = x ;
        x = floor [ i ] [ 1 ] ;
        floor [ i ] [ 1 ] = floor [ j ] [ 1 ] ;
        floor [ j ] [ 1 ] = x ;
      }
    }
    t += s - floor [ i ] [ 0 ] ;
    s = floor [ i ] [ 0 ] ;
    if ( floor [ i ] [ 1 ] > t ) {
      t = floor [ i ] [ 1 ] ;
    }
  }
  System . out . println ( t + s ) ;
}

public static void main ( String [ ] args ) { Scanner scan = new Scanner ( System . in ) ; int n = scan . nextInt ( ) ; int s = scan . nextInt ( ) ; int [ ] [ ] floor = new int [ n ] [ 2 ] ; int t = 0 ; for ( int i = 0 ; i < n ; i ++ ) { floor [ i ] [ 0 ] = scan . nextInt ( ) ; floor [ i ] [ 1 ] = scan . nextInt ( ) ; } for ( int i = 0 ; i < n ; i ++ ) { for ( int j = i + 1 ; j < n ; j ++ ) { if ( floor [ i ] [ 0 ] < floor [ j ] [ 0 ] ) { int x = floor [ i ] [ 0 ] ; floor [ i ] [ 0 ] = floor [ j ] [ 0 ] ; floor [ j ] [ 0 ] = x ; x = floor [ i ] [ 1 ] ; floor [ i ] [ 1 ] = floor [ j ] [ 1 ] ; floor [ j ] [ 1 ] = x ; } } t += s - floor [ i ] [ 0 ] ; s = floor [ i ] [ 0 ] ; if ( floor [ i ] [ 1 ] > t ) { t = floor [ i ] [ 1 ] ; } } System . out . println ( t + s ) ; }
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name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier)) dimensions: (dimensions_expr (decimal_integer_literal))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (expression_statement (assignment_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (decimal_integer_literal)) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (assignment_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: 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