#include <algorithm>
#include <iostream>
 
std::size_t count_unique(const std::vector<int>& v)
{
    std::size_t count = 0;
 
    for (auto it = v.begin(); it != v.end(); )
    {
        auto it2 = std::find_if(it + 1, v.end(), [&](int e) { return e != *it; });
        count += (it2 - it == 1);
        it = it2;
    }
    return count;
}
 
int main()
{
    std::cout << count_unique({4, 4, 5, 5, 6, 7}) << std::endl; // 2
    std::cout << count_unique({2, 3, 3, 4, 5, 5, 6, 7, 7}) << std::endl; // 3
}
 

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