class Solution {
public:
    int countStudents(vector<int>& students, vector<int>& sandwiches) {
    vector<int> cnt(2);
    for (auto s : students) cnt[s]++;
    auto stu = students.begin();
    auto san = sandwiches.begin();
    for (;san < sandwiches.end();)
    {
        if (*stu != *san)
        {
            if (cnt[*san] == 0)
            {
                break;
            }
            int tmp = *stu;
            stu = students.erase(stu);
            students.push_back(tmp);
            
        }
        else
        {
            cnt[*stu]--;
            stu = students.erase(stu);
            san = sandwiches.erase(san);
            
        }

    }
    return students.size();
}
};