Why this answer for test 1 gets WA

2 3
1 2
3 4 5

?????????

algorithm is just
print on
1 ... n
then n+1 ... n+m

what's wroung with this???????????????

The algorithm is not
1 ... n
n+1 ... n+m

In your answer
1 + 4 = 2 + 3

This violates the condition "Ivan Vasil'evich considered all the possible variants and saw that this was impossible"