public static void main ( String [ ] args ) throws InterruptedException {
  Scanner in = new Scanner ( System . in ) ;
  int N = in . nextInt ( ) ;
  int M = in . nextInt ( ) ;
  Set < Integer > from1 = new TreeSet < Integer > ( ) ;
  Set < Integer > toN = new TreeSet < Integer > ( ) ;
  for ( int i = 0 ;
  i < M ;
  i ++ ) {
    int s = in . nextInt ( ) ;
    int g = in . nextInt ( ) ;
    if ( s == 1 && ! from1 . contains ( g ) ) {
      from1 . add ( g ) ;
    }
    else if ( g == N && ! toN . contains ( s ) ) {
      toN . add ( s ) ;
    }
  }
  String answer = "IMPOSSIBLE" ;
  for ( int island : from1 ) {
    if ( toN . contains ( island ) ) {
      answer = "POSSIBLE" ;
      break ;
    }
  }
  System . out . println ( answer ) ;
}

public static void main ( String [ ] args ) throws InterruptedException { Scanner in = new Scanner ( System . in ) ; int N = in . nextInt ( ) ; int M = in . nextInt ( ) ; Set < Integer > from1 = new TreeSet < Integer > ( ) ; Set < Integer > toN = new TreeSet < Integer > ( ) ; for ( int i = 0 ; i < M ; i ++ ) { int s = in . nextInt ( ) ; int g = in . nextInt ( ) ; if ( s == 1 && ! from1 . contains ( g ) ) { from1 . add ( g ) ; } else if ( g == N && ! toN . contains ( s ) ) { toN . add ( s ) ; } } String answer = " IMPOSSIBLE " ; for ( int island : from1 ) { if ( toN . contains ( island ) ) { answer = " POSSIBLE " ; break ; } } System . out . println ( answer ) ; }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (type_identifier) dimensions: (dimensions)) name: (identifier))) (throws (type_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: (generic_type (type_identifier) (type_arguments (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments (type_identifier))) arguments: (argument_list)))) (local_variable_declaration type: (generic_type (type_identifier) (type_arguments (type_identifier))) declarator: (variable_declarator name: (identifier) value: (object_creation_expression type: (generic_type (type_identifier) (type_arguments (type_identifier))) 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)))) (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (decimal_integer_literal)) right: (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) consequence: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))) alternative: (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (unary_expression operand: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))))) consequence: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))))))))) (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (string_literal))) (enhanced_for_statement type: (integral_type) name: (identifier) value: (identifier) body: (block (if_statement condition: (parenthesized_expression (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier)))) consequence: (block (expression_statement (assignment_expression left: (identifier) right: (string_literal))) (break_statement))))) (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))