Identify the oxidizing agent and reducing agent

[Suy]

1. The problem statement, all variables and given/known data
Sn(s)+NO3--->SnO2(s)+NO(g)


2. Relevant equations



3. The attempt at a solution
0 |+5 ,-2| |+4,-2| |+2,-2|
Sn(s)+NO3--->SnO2(s)+NO(g)
Sn lost 4e reducing agent
N gain 3e oxidizing agent
is that right?
What about oxygen?? do i do the same thing?
thanks

[Firelion]

The Oxygen is neither gained nor lost electrons. It stays by -2.
and yes I thibk you`re right.