public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int h = sc . nextInt ( ) ;
  int w = sc . nextInt ( ) ;
  int n = sc . nextInt ( ) ;
  HashMap < Integer , TreeSet < Integer >> map = new HashMap < > ( ) ;
  for ( int i = 1 ;
  i <= h ;
  i ++ ) {
    map . put ( i , new TreeSet < > ( ) ) ;
  }
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    int x = sc . nextInt ( ) ;
    int y = sc . nextInt ( ) ;
    map . get ( x ) . add ( y ) ;
  }
  int yMax = 1 ;
  for ( int i = 2 ;
  i <= h ;
  i ++ ) {
    if ( map . get ( i ) . isEmpty ( ) ) {
      yMax ++ ;
    }
    else if ( map . get ( i ) . first ( ) <= yMax ) {
      System . out . println ( i - 1 ) ;
      return ;
    }
    else if ( map . get ( i ) . first ( ) > yMax + 1 ) {
      yMax ++ ;
    }
  }
  System . out . println ( h ) ;
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int h = sc . nextInt ( ) ; int w = sc . nextInt ( ) ; int n = sc . nextInt ( ) ; HashMap < Integer , TreeSet < Integer > > map = new HashMap < > ( ) ; for ( int i = 1 ; i <= h ; i ++ ) { map . put ( i , new TreeSet < > ( ) ) ; } for ( int i = 0 ; i < n ; i ++ ) { int x = sc . nextInt ( ) ; int y = sc . nextInt ( ) ; map . get ( x ) . add ( y ) ; } int yMax = 1 ; for ( int i = 2 ; i <= h ; i ++ ) { if ( map . get ( i ) . isEmpty ( ) ) { yMax ++ ; } else if ( map . get ( i ) . first ( ) <= yMax ) { System . out . println ( i - 1 ) ; return ; } else if ( map . get ( i ) . first ( ) > yMax + 1 ) { yMax ++ ; } } System . out . println ( h ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (type_identifier) arguments: (argument_list (field_access object: (identifier) field: (identifier)))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (type_identifier) (generic_type (type_identifier) (type_arguments (type_identifier))))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments)) arguments: (argument_list)))) (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 (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (object_creation_expression type: (generic_type (type_identifier) (type_arguments)) arguments: (argument_list))))))) (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 (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) name: (identifier) arguments: (argument_list (identifier)))))) (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 (if_statement condition: (parenthesized_expression (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) name: (identifier) arguments: (argument_list))) consequence: (block (expression_statement (update_expression (identifier)))) alternative: (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) name: (identifier) arguments: (argument_list)) right: (identifier))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal))))) (return_statement)) alternative: (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) name: (identifier) arguments: (argument_list)) right: (binary_expression left: (identifier) right: (decimal_integer_literal)))) consequence: (block (expression_statement (update_expression (identifier))))))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))