Please give error solutions and explain it please

Question

https://code.sololearn.com/cJUoXC2hxp8s/?ref=app
Please give error solutions and explain it please

Answer 1

://remove double 0 from 7 and 8, it's value less

long x=7;
long y=8;
System.out.println (++x+y--);

Answer 2

But it accepts the value of 007 why is not accepted 008?