999999 + 1 = 1000000
999999 + 2 = 1000001
999999 + 3 = 1000002
999999 + 4 = 1000003
999999 + 5 = 1000004
999999 + 6 = 1000005
999999 + 7 = 1000006
999999 + 8 = 1000007
999999 + 9 = 1000008
1000 + 1 = 1001
1000 + 2 = 1002
1000 + 3 = 1003
1000 + 4 = 1004
1000 + 5 = 1005
1000 + 6 = 1006
1000 + 7 = 1007
1000 + 8 = 1008
1000 + 9 = 1009