I have an interesting problem for you.
Well, this is a problem from Gordian Knot '15. And, I shall be bold enough to assume that it succeeded in engrossing you :)
Felicity Threads of IIIT Hyderabad would like to invite you to participate in Gordian Knot, a Project Euler style mathematical contest. For the real world counterparts of Charlie Eppes, of Numb3rs, this contest promises to be an enthralling experience especially if your forte is the field of mathematics and computing.
Contest Start: 0000 HRS IST (UTC +0530 HRS), January 10 2016
Contest End: 0000 HRS IST (UTC +0530 HRS), January 11 2016
Click here to go to the contest
Follow live updates! :D
Prizes worth INR 15k to be won!
And, if that isn't enough, there's always bragging rights! ;)
Just have a look at last year's final standings :)
P.S. The answer is 999999999996