Addition Error!

Mike added all positive integers from 1 to n on his calculator and obtained a total of 2015. By mistake, however, he had entered one number twice. Find the correct total $a$ that Mike should have obtained and the number $b$ that he added twice.

Write the answers separated by a period, $(a.b)$ .

For example, if you think that $a = 100, b= 35$ is the solution, submit your answer as 100.35.