Write a program to print sum of an AP with n terms with first term a and common difference d.
The first line of the input contains T denoting the number of testcases. The first line of the test case will be the number of terms of AP and second line its first term and common difference.
For each test case, output will be the sum of AP
1 <= T<= 100
1 <= N <= 1000
1 <= a,d <= 100