public static void main ( String [ ] args ) throws Exception {
  BufferedReader input = new BufferedReader ( new InputStreamReader ( System . in ) ) ;
  String number = input . readLine ( ) ;
  int n = number . length ( ) ;
  input . close ( ) ;
  long [ ] dp = new long [ n + 1 ] ;
  dp [ 0 ] = 0 ;
  for ( int i = 1 ;
  i <= n ;
  i ++ ) {
    int lastDigit = number . charAt ( i - 1 ) - '0' ;
    int lastTwoDigits = - 1 ;
    if ( i >= 2 ) {
      lastTwoDigits = ( number . charAt ( i - 2 ) - '0' ) * 10 + lastDigit ;
    }
    dp [ i ] = dp [ i - 1 ] ;
    if ( lastDigit % 4 == 0 ) {
      dp [ i ] ++ ;
    }
    if ( lastTwoDigits % 4 == 0 ) {
      dp [ i ] += ( i - 1 ) ;
    }
  }
  PrintWriter output = new PrintWriter ( System . out ) ;
  output . println ( dp [ n ] ) ;
  output . close ( ) ;
}

public static void main ( String [ ] args ) throws Exception { BufferedReader input = new BufferedReader ( new InputStreamReader ( System . in ) ) ; String number = input . readLine ( ) ; int n = number . length ( ) ; input . close ( ) ; long [ ] dp = new long [ n + 1 ] ; dp [ 0 ] = 0 ; for ( int i = 1 ; i <= n ; i ++ ) { int lastDigit = number . charAt ( i - 1 ) - '0' ; int lastTwoDigits = - 1 ; if ( i >= 2 ) { lastTwoDigits = ( number . charAt ( i - 2 ) - '0' ) * 10 + lastDigit ; } dp [ i ] = dp [ i - 1 ] ; if ( lastDigit % 4 == 0 ) { dp [ i ] ++ ; } if ( lastTwoDigits % 4 == 0 ) { dp [ i ] += ( i - 1 ) ; } } PrintWriter output = new PrintWriter ( System . out ) ; output . println ( dp [ n ] ) ; output . close ( ) ; }
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