VTMO 2019 — Grade 8 — semifinal Question 10

Start with $D = \{ 1 , 2 , 3 , 4 , 5 , 6 , 7 \}$. Each move decreases one entry $1$ and increases another $5$. Finally $D = \{ 2012 , 2013 , 2014 , 2015 , 2016 , 2017 , x \}$. Which $x$ is possible?