Hi, my upstairs neighbour' cat keeps coming to our window and crying or jumping in a window.
Last night he came to the window around 1am, it was freezing outside so I went to the front door and he was practically in before I got the door opened. He came in and wandered and cried and done the rubbing up against our leg thing, he was like an ice block. I got worried and gave him a bit of food. 
Shut us both in the kitchen so he could have it as my 3 were trying to get to him, and although he was scared and kept looking over his shoulder and fidgety he ate the lot in seconds and DP let him out.
I'm slighly worried about him now, he's just been back crying again but my cats chased him out. He's only a wee thing and is 1yo but is out constantly, the neighbour says he stays out all night which we didn't know as have previously knocked on their door to let him in when he's been crying at ours and he dashed in when they opened the door. It doesn't seem like he actually wants to be out and now it's so cold I am really worried.
We fed him for a few days while they were away and they said he gets half a tin in the morning and the other half later and a little bit of mix.
Is this enough for a cat who is constantly outside, all day and all night?