--- list = &els[0]
0 (prev 0 next -1)
1 (prev 9 next 9)
2 (prev 9 next 9)
3 (prev 9 next 9)
4 (prev 9 next 9)
--- list = &els[1]
0 (prev 1 next -1)
1 (prev 0 next 0)
2 (prev 9 next 9)
3 (prev 9 next 9)
4 (prev 9 next 9)
--- list = &els[2]
0 (prev 2 next 1)
1 (prev 0 next -1)
2 (prev 1 next 0)
3 (prev 9 next 9)
4 (prev 9 next 9)
--- list = &els[3]
0 (prev 1 next 2)
1 (prev 3 next 0)
2 (prev 0 next -1)
3 (prev 2 next 1)
4 (prev 9 next 9)
--- list = &els[4]
0 (prev 2 next 1)
1 (prev 0 next 3)
2 (prev 4 next 0)
3 (prev 1 next -1)
4 (prev 3 next 2)
--- list = &els[0]
0 (prev 0 next 0)
1 (prev 9 next 9)
2 (prev 9 next 9)
3 (prev 9 next 9)
4 (prev 9 next 9)
--- list = &els[1]
0 (prev 1 next 1)
1 (prev 0 next 0)
2 (prev 9 next 9)
3 (prev 9 next 9)
4 (prev 9 next 9)
--- list = &els[2]
0 (prev 2 next 1)
1 (prev 0 next 2)
2 (prev 1 next 0)
3 (prev 9 next 9)
4 (prev 9 next 9)
--- list = &els[3]
0 (prev 1 next 2)
1 (prev 3 next 0)
2 (prev 0 next 3)
3 (prev 2 next 1)
4 (prev 9 next 9)
--- list = &els[4]
0 (prev 2 next 1)
1 (prev 0 next 3)
2 (prev 4 next 0)
3 (prev 1 next 4)
4 (prev 3 next 2)