Update relative frequency of { p , q , r , s }
if ( mp . ContainsKey ( new Tuple < Tuple < int , int > , Tuple < int , int > > ( new Tuple < int , int > ( p , q ) , new Tuple < int , int > ( r , s ) ) ) ) { mp [ new Tuple < Tuple < int , int > , Tuple < int , int > > ( new Tuple < int , int > ( p , q ) , new Tuple < int , int > ( r , s ) ) ] ++ ; } else { mp [ new Tuple < Tuple < int , int > , Tuple < int , int > > ( new Tuple < int , int > ( p , q ) , new Tuple < int , int > ( r , s ) ) ] = 1 ; } }