This issue is on these lines:

```
vector<int> temp(subsets_a.begin(), subsets_a.end());
temp.insert(temp.end(),subsets_b.begin(), subsets_b.end());
```

Here temp is of type vector<`int`

>, but subsets_a and subsets_b are of type vector<vector<`int`

>>.

Since the value types are int and vector<`int`

> respectively, they don't match, and so this doesn't compile. Depending on what you need, either make temp a vector<vector<`int`

>>, or copy the individual ints in each vector of subsets_a and subsets_b into temp.