public static void main ( String [ ] args ) throws IOException {
  BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  PrintWriter pw = new PrintWriter ( System . out ) ;
  int t = 1 ;
  while ( t -- > 0 ) {
    char a [ ] = br . readLine ( ) . trim ( ) . toCharArray ( ) ;
    int n = a . length ;
    int i = 0 ;
    for ( ;
    i < n ;
    i ++ ) {
      if ( a [ i ] == '[' ) break ;
    }
    int j = i + 1 ;
    for ( ;
    j < n ;
    j ++ ) {
      if ( a [ j ] == ':' ) break ;
    }
    int k = n - 1 ;
    for ( ;
    k >= 0 ;
    k -- ) {
      if ( a [ k ] == ']' ) break ;
    }
    int l = k - 1 ;
    for ( ;
    l >= 0 ;
    l -- ) {
      if ( a [ l ] == ':' ) break ;
    }
    if ( j < l ) {
      int count = 0 ;
      for ( int p = j + 1 ;
      p < l ;
      p ++ ) {
        if ( a [ p ] == '|' ) count ++ ;
      }
      pw . println ( count + 4 ) ;
    }
    else {
      pw . println ( - 1 ) ;
    }
  }
  pw . flush ( ) ;
}

public static void main ( String [ ] args ) throws IOException { BufferedReader br = new BufferedReader ( new InputStreamReader ( System . in ) ) ; PrintWriter pw = new PrintWriter ( System . out ) ; int t = 1 ; while ( t -- > 0 ) { char a [ ] = br . readLine ( ) . trim ( ) . toCharArray ( ) ; int n = a . length ; int i = 0 ; for ( ; i < n ; i ++ ) { if ( a [ i ] == ' [ ' ) break ; } int j = i + 1 ; for ( ; j < n ; j ++ ) { if ( a [ j ] == ' : ' ) break ; } int k = n - 1 ; for ( ; k >= 0 ; k -- ) { if ( a [ k ] == ' ] ' ) break ; } int l = k - 1 ; for ( ; l >= 0 ; l -- ) { if ( a [ l ] == ' : ' ) break ; } if ( j < l ) { int count = 0 ; for ( int p = j + 1 ; p < l ; p ++ ) { if ( a [ p ] == ' | ' ) count ++ ; } pw . println ( count + 4 ) ; } else { pw . println ( - 1 ) ; } } pw . flush ( ) ; }
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(if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (character_literal))) consequence: (break_statement)))) (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (decimal_integer_literal)))) (for_statement condition: (binary_expression left: (identifier) right: (decimal_integer_literal)) update: (update_expression (identifier)) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (array_access array: (identifier) index: (identifier)) right: (character_literal))) consequence: (break_statement)))) (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (identifier))) consequence: (block (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: (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: (array_access array: (identifier) index: (identifier)) right: (character_literal))) consequence: (expression_statement (update_expression (identifier)))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (binary_expression left: (identifier) right: (decimal_integer_literal)))))) alternative: (block (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list (unary_expression operand: (decimal_integer_literal))))))))) (expression_statement (method_invocation object: (identifier) name: (identifier) arguments: (argument_list)))))