public static void main ( String [ ] args ) {
  Scanner sc = new Scanner ( System . in ) ;
  int N = sc . nextInt ( ) ;
  int M = sc . nextInt ( ) ;
  int [ ] [ ] adj = new int [ N ] [ N ] ;
  for ( int i = 0 ;
  i < N ;
  ++ i ) for ( int j = 0 ;
  j < N ;
  ++ j ) adj [ i ] [ j ] = 1 << 28 ;
  for ( int i = 0 ;
  i < M ;
  ++ i ) {
    int u = sc . nextInt ( ) - 1 ;
    int v = sc . nextInt ( ) - 1 ;
    int w = sc . nextInt ( ) ;
    adj [ u ] [ v ] = adj [ v ] [ u ] = w ;
  }
  for ( int k = 1 ;
  k < N ;
  ++ k ) {
    for ( int i = 1 ;
    i < N ;
    ++ i ) {
      for ( int j = 1 ;
      j < N ;
      ++ j ) {
        if ( adj [ i ] [ j ] > adj [ i ] [ k ] + adj [ k ] [ j ] ) {
          adj [ i ] [ j ] = adj [ i ] [ k ] + adj [ k ] [ j ] ;
        }
      }
    }
  }
  int minD = 1 << 28 ;
  for ( int i = 1 ;
  i < N ;
  ++ i ) {
    for ( int j = i + 1 ;
    j < N ;
    ++ j ) {
      if ( adj [ 0 ] [ i ] == 1 << 28 || adj [ 0 ] [ j ] == 1 << 28 ) continue ;
      minD = Math . min ( minD , adj [ 0 ] [ i ] + adj [ 0 ] [ j ] + adj [ i ] [ j ] ) ;
    }
  }
  if ( minD == 1 << 28 ) {
    System . out . println ( - 1 ) ;
  }
  else {
    System . out . println ( minD ) ;
  }
}

public static void main ( String [ ] args ) { Scanner sc = new Scanner ( System . in ) ; int N = sc . nextInt ( ) ; int M = sc . nextInt ( ) ; int [ ] [ ] adj = new int [ N ] [ N ] ; for ( int i = 0 ; i < N ; ++ i ) for ( int j = 0 ; j < N ; ++ j ) adj [ i ] [ j ] = 1 << 28 ; for ( int i = 0 ; i < M ; ++ i ) { int u = sc . nextInt ( ) - 1 ; int v = sc . nextInt ( ) - 1 ; int w = sc . nextInt ( ) ; adj [ u ] [ v ] = adj [ v ] [ u ] = w ; } for ( int k = 1 ; k < N ; ++ k ) { for ( int i = 1 ; i < N ; ++ i ) { for ( int j = 1 ; j < N ; ++ j ) { if ( adj [ i ] [ j ] > adj [ i ] [ k ] + adj [ k ] [ j ] ) { adj [ i ] [ j ] = adj [ i ] [ k ] + adj [ k ] [ j ] ; } } } } int minD = 1 << 28 ; for ( int i = 1 ; i < N ; ++ i ) { for ( int j = i + 1 ; j < N ; ++ j ) { if ( adj [ 0 ] [ i ] == 1 << 28 || adj [ 0 ] [ j ] == 1 << 28 ) continue ; minD = Math . min ( minD , adj [ 0 ] [ i ] + adj [ 0 ] [ j ] + adj [ i ] [ j ] ) ; } } if ( minD == 1 << 28 ) { System . out . println ( - 1 ) ; } else { System . out . println ( minD ) ; } }
(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: (array_type element: (integral_type) dimensions: (dimensions)) declarator: (variable_declarator name: (identifier) value: (array_creation_expression type: (integral_type) dimensions: (dimensions_expr (identifier)) dimensions: (dimensions_expr (identifier))))) (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: (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: (expression_statement (assignment_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (binary_expression left: (decimal_integer_literal) right: (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 (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (decimal_integer_literal)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)) right: (decimal_integer_literal)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))) (expression_statement (assignment_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (assignment_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (identifier)))))) (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 (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 (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 (binary_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (binary_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier))))) consequence: (block (expression_statement (assignment_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (binary_expression left: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier)) right: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier))))))))))))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (decimal_integer_literal) right: (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 (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (decimal_integer_literal)))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (binary_expression left: (array_access array: (array_access array: (identifier) index: (decimal_integer_literal)) index: (identifier)) right: (binary_expression left: (decimal_integer_literal) right: (decimal_integer_literal))) right: (binary_expression left: (array_access array: (array_access array: (identifier) index: (decimal_integer_literal)) index: (identifier)) right: (binary_expression left: (decimal_integer_literal) right: (decimal_integer_literal))))) consequence: (continue_statement)) (expression_statement (assignment_expression left: (identifier) right: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier) (binary_expression left: (binary_expression left: (array_access array: (array_access array: (identifier) index: (decimal_integer_literal)) index: (identifier)) right: (array_access array: (array_access array: (identifier) index: (decimal_integer_literal)) index: (identifier))) right: (array_access array: (array_access array: (identifier) index: (identifier)) index: (identifier))))))))))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (binary_expression left: (decimal_integer_literal) right: (decimal_integer_literal)))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (unary_expression operand: (decimal_integer_literal)))))) alternative: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier))))))))