What one Purdue University graduate thought was an easy A turned out to be a major failure.

Roy Sun, 25, was sentenced on Feb. 27 to a four-year prison term for hacking into the university’s computer system to change his and several other student’s course grades. According to the Journal and Courier, it was ruled that Sun will serve a total of 90 days in jail. The rest of his sentence will be with four years of supervised probation and 100 hours of community service.

The scheme first kicked off in 2008 when Sun changed a single course grade to test if he Purdue student Mitsutoashi Shirasaki would get caught. After successfully altering the one grade without anyone noticing the change, Sun said he felt invincible. “When I came back in 2009, I felt really arrogant. I thought I was untouchable,” Sun said during his sentencing last week. "It became so much easier to change my grades than going to class and working real hard.”

During his senior year, Sun missed all of his classes but one. However, with the help of the pair’s scheme, he was still able to receive straight A’s. Sun and Shirasaki had become so brazen that they would hack into professor’s computers just around 10 minutes before their final grades were submitted. They even changed the grade of a third friend, Sujay Sharma. Sharma wasn’t aware that his grade was changed, but he did serve as a lookout for the two.

They were able to successfully gain access to their professor’s information by installing keystroke logging software onto the professors’ computers. Or if a professor entered grades remotely, Sun would hack into the instructor’s personal information to gain access to their accounts. According to Boston.com, the affidavit revealed that Sun changed eight F’s and one D to all A’s. Shiraski changed his grades from F’s, D’s and C’s to all B’s and A’s. Shiraski was even accused of changing one of his girlfriend’s grades from an A to an A+.

Sun and Sharma both pled guilty to their charges in the case on Dec. 30. Sun faced charges that included computer tampering and conspiracy to commit computer tampering. Sun was also expelled from his graduate program at Boston University and stripped of his bachelor’s degree from Purdue – the same degree that landed him a $70,000 per year job straight out of undergrad. He left his post-college job to go back to grad school. BU spokesman Colin Riley confirmed to Boston.com that Sun had been enrolled in a BU grad program for one semester.

Sharma was sentenced to 18 months of probation and 200 hours of community service. Sharma had just one class remaining after studying nuclear engineering at Purdue for six years. But he was expelled after a review from the Office of the Dean of Students, reports the Purdue Exponent. Shirasaki fled to Japan at Sun’s request.