I don't know what country you live in or what the laws and practical circumstances of owning rental property there are. But I own a rental property in the U.S., and I can tell you that there are a lot of headaches that go with it.
One: Maintenance. You say you have to pay an annual fee of 2,400 for "building maintenance". Does that cover all maintenance to the unit or only the exterior? I mean, here in the U.S. if you own a condo (we call a unit like you describe a "condo" -- if you rent it, it's an apartment; if you own it, it's a condo) you typically pay an annual fee that cover maintenance "from the walls out", that is, it covers maintenance to the exterior of the building, the parking lot, any common recreational areas like a swimming pool, etc. But it doesn't cover interior maintenance. If there's a problem with interior wiring or plumbing or the carpet needs to be replaced or the place needs painting, that's up to you.
With a rental unit, those expenses can be substantial. On my rental property, sure, most months the maintenance is zero: things don't break every month. But if the furnace needs to be replaced or there's a major plumbing problem, it can cost thousands. And you can get hit with lots of nitnoid expenses. While my place was vacant I turned the water heater down to save on utility expenses. Then a tenant moved in and complained that the water heater didn't work. We sent a plumber out who quickly figured out that she didn't realize she had to turn the knob up. Then of course he had to hang around while the water heated up to make sure that was all it was. It cost me, umm, I think $170 to have someone turn that knob. (But I probably saved over $15 on the gas bill by turning it down for the couple of months the place was empty!)
Two: What happens when you get a bad tenant? Here in the U.S., theoretically you only have to give 3 days notice to evict a tenant who damages the property or fails to pay the rent. But in practice, they don't leave. Then you have to go to court to get the police to throw them out. When you contact the court, they will schedule a hearing in a month or two. If your case is clear cut -- like the tenant hasn't paid the rent for two months or more -- you will win easily. Both times I've had to do this the tenant didn't even bother to show up so I won by default. So then you have a piece of paper saying the court orders them to leave. You have to wait another month or two for the police to get around to actually going to the unit and ordering them out. So say a tenant fails to pay the rent. In real life you're probably not going to evict someone for being a day or two late, but let's say you're pretty hard-nosed about it and start eviction proceedings when they're a month late. There's at least another two or three months before they're actually going to be out of the place. Of course once you send them an eviction notice they're not going to pay the rent any more. So you have to go four, five months with these people living in your property but not paying any rent.
On top of that, some tenants do serious damage to the property. It's not theirs: they don't have much incentive to take care of it. If you evict someone, they may deliberately trash the place out of spite. One tenant I had to evict did over $13,000 in damage.
So I'm not saying, don't rent the place out. What I am saying is, be sure to include all your real costs in your calculation. Think of all the things that could go wrong as well as all the things that could go right.