static int countOccurrences ( String s , int K ) {
  int n = s . length ( ) ;
  int C = 0 , c1 = 0 , c2 = 0 ;
  for ( int i = 0 ;
  i < n ;
  i ++ ) {
    if ( s . charAt ( i ) == 'a' ) c1 ++ ;
    if ( s . charAt ( i ) == 'b' ) {
      c2 ++ ;
      C += c1 ;
    }
  }
  return C * K + ( K * ( K - 1 ) / 2 ) * c1 * c2 ;
}

static int countOccurrences ( String s , int K ) { int n = s . length ( ) ; int C = 0 , c1 = 0 , c2 = 0 ; for ( int i = 0 ; i < n ; i ++ ) { if ( s . charAt ( i ) == ' a ' ) c1 ++ ; if ( s . charAt ( i ) == ' b ' ) { c2 ++ ; C += c1 ; } } return C * K + ( K * ( K - 1 ) / 2 ) * c1 * c2 ; }
(method_declaration (modifiers) type: (integral_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (type_identifier) name: (identifier)) (formal_parameter type: (integral_type) name: (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: (decimal_integer_literal)) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal)) 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 (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (character_literal))) consequence: (expression_statement (update_expression (identifier)))) (if_statement condition: (parenthesized_expression (binary_expression left: (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (identifier))) right: (character_literal))) consequence: (block (expression_statement (update_expression (identifier))) (expression_statement (assignment_expression left: (identifier) right: (identifier))))))) (return_statement (binary_expression left: (binary_expression left: (identifier) right: (identifier)) right: (binary_expression left: (binary_expression left: (parenthesized_expression (binary_expression left: (binary_expression left: (identifier) right: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal)))) right: (decimal_integer_literal))) right: (identifier)) right: (identifier))))))