list<pair<,>> :: iterator vs vector<list<pair<,>>>: is there a simple way to search an element in these 2? find() isn't helpful

I have to search a {key, value} pair in a vector<list<pair<int, int>>>. There are 2 ways I tried doing this:

1. Using an iterator

   list<pair<int, int>> :: iterator search(int key)
    {
        int h = hash_func(key);
        auto itr = v[h].begin();
        while(itr!=v[h].end())
        {
            if(itr->first==key)
                return itr;
            itr++;
        }
        return itr;
    }
   

   This approach works just fine!

2. However, I tried another approach - using find() function

   list<pair<int, int>> :: iterator search(int key)
    {
        int h = hash_func(key);
        return find(v[h].begin(), v[h].end(), key);
    }
   

   I'm getting the following error:

error: invalid operands to binary expression ('std::pair<int, int>' and 'const int') { return *__it == _M_value; }

I'm still new to STL and have not been able to figure out where I'm going wrong!

I'm aware that the find function is supposed to return an iterator pointing to a {key, value} pair. The fact that I'm using a list of pair, will I still be needing to update some iterator as I was doing in the 1st approach?