C. Dreamoon and Sumstime limit per test1.5 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputDreamoon loves summing up something for no reason. One day he obtains two integers a and b occasionally. He wants to calculate the sum of all nice integers. Positive integer x is called nice if  and , where k is some integer number in range [1, a].By  we denote the quotient of integer division of x and y. By  we denote the remainder of integer division of x and y. You can read more about these operations here: http://goo.gl/AcsXhT.The answer may be large, so please print its remainder modulo 1 000 000 007 (109 + 7). Can you compute it faster than Dreamoon?InputThe single line of the input contains two integers a, b (1 ≤ a, b ≤ 107).OutputPrint a single integer representing the answer modulo 1 000 000 007 (109 + 7).ExamplesInput1 1Output0Input2 2Output8NoteFor the first sample, there are no nice integers because  is always zero.For the second sample, the set of nice integers is {3, 5}.
Input1 1
Output0
['math', '*1600']