About the indicator of reid model in evaluate.py

why dose the top1correct indicator can get from using `res = scores.topk(5, dim=1)[1][:,0]` as the code below&#65311;

```
res = scores.topk(5, dim=1)[1][:,0]
top1correct = gl[res].eq(ql).sum().item()
```

why not using  `res = scores.topk(1, dim=1)[1][:,0]`

