B"You are given a multiset S . Over all pairs of subsets A and B , such that: find the sum of sum_{x in A}{x} cdot sum_{x in B}{x} , modulo 998 ,244 ,353 . The first line contains one integer m ( 1 <= m <= 10^5 ): the number of different values in the multiset S . Each of the next m lines contains two integers a_i , freq_i ( 1 <= a_i <= 10^5, 1 <= freq_i <= 10^9 ). Element a_i appears in the multiset S freq_i times. All a_i are different. Print the required sum, modulo 998 ,244 ,353 . A multiset is a set where elements are allowed to coincide. |X| is the cardinality of a set X , the number of elements in it. A subset B : Set A is a subset of a set B . In the first example B= {1 }, A= {1,2 } and B= {2 }, A= {1, 2 } have a product equal to 1 cdot3 + 2 cdot3=9 . Other pairs of A and B don't satisfy the given constraints. "...