After setting up the area. Chandu wanted all his toys to be stacked there in that area. So that all of them are accessible easily. Currently, He is having N stacks of toys each with height \(H_1,H_2...H_n\) (assuming all toys are of same height).Chandu did not like the configuration much and want to change the height of each stack. To increase the height of a particular stack he can add some toys to it and to decrease the height he can take out some toys from that stack. Chandu, knows that he requires X units of effort for putting up an item onto the stack and Y units of effort for removing it. Help, chandu in setting up his toys.
Input:
First Line of input contains an integer t, which is the number of test cases. then, t lines follow where first line of each test case contains three integers N, X and Y then N lines follow containing two integers each \(a[i]\) and \(b[i]\) (Initial height of \(i\;th\) stack and final height of \(i\;th\) stack.)
Output:
Output an integer which is the minimum effort required.
NOTE: he just need to make stacks of given height. Not necessarily each stack should be made from its corresponding stack.
Constraints:
\(1 \le t \le 100, \)
\(1 \le N \le 10^5, \)
\(1 \le a[i],b[i] \le 10^6\)
Here, He is having 3 stacks initially of height \(3,1\) and 1 He can take out one toy from first stack to get a stack with two toys with 4 units of effort. He can put toy on second stack to get a stack with two toys with 6 units of effort. Total effort = \(10\) units. After the two operations he will have three stacks with required heights.