Adiciones

x = 1
y = 2
x = 12
y = 121
x = 122
y = 211
x = 222
y = 333

x = 400
y = 401
x = 402
y = 500
x = 600
y = 1000
x = 1001
y = 2000
x = 2001
y = 3000
x = 4000
y = 5000
x = 5001
y = 6000

x = 9999
y = 10 000
x = 99 999
y = 999 999

x = 0 - 1

y = x