It's not a chord!

Solve at least 50 problems as official contestant in C#

Eugene1, first achieved on Sept. 27, 2012

Hadi_Asiaie1, first achieved on Dec. 28, 2010

AnatolyTolstobrov1, first achieved on Jan. 12, 2017

lionvs131, first achieved on Sept. 6, 2017

maslowmw1, first achieved on April 21, 2012

dwoolley31, first achieved on May 12, 2013

it4.kp1, first achieved on Dec. 6, 2012

Zvigintsev1, first achieved on May 5, 2016

chokudai1, first achieved on July 17, 2013

artsin6661, first achieved on March 27, 2017

tanzaku1, first achieved on Jan. 4, 2011

Neverauskas1, first achieved on Oct. 17, 2015

kuuso1, first achieved on Sept. 12, 2014

azukun1, first achieved on Dec. 30, 2014

camypaper1, first achieved on April 26, 2015

fiver1, first achieved on April 24, 2012

Kavir1, first achieved on March 10, 2014

T-D-K1, first achieved on April 25, 2014

alexandr.vladimirov1, first achieved on Oct. 10, 2013

DigitalArtist1, first achieved on June 8, 2016