#include <algorithm>
#include <vector>

int minAvgTwoSlice(const std::vector<int>& a)
{
    int idx = 0;
    double min = (a[0] + a[1]) / 2.0;

    for (std::size_t i = 0; i + 1 < a.size(); ++i) {
        double cur = (a[i] + a[i + 1]) / 2.0;
        if (i + 2 < a.size()) {
            double three = (a[i] + a[i + 1] + a[i + 2]) / 3.0;
            cur = std::min(cur, three);
        }
        if (cur < min) {
            min = cur;
            idx = static_cast<int>(i);
        }
    }

    return idx;
}