z + x + w + y = 5988
x = z + 1
w = z + 2
y = z + x + w - 12
y = z + z + 1 + z + 2 - 12
y = 3z - 9
z + z + 1 + z + 2 + 3z - 9 = 5988
6z - 6 = 5988
6z = 5994
z = 999
x = a + 1
w = 1000
w = a + 2
w = 1001
y = 3a - 9
y = 2997 - 9
y = 2988
999 + 1000 + 1001 + 2988 = 5988
3000 + 2988 = 5988
5988 = 5988