#include <algorithm>
#include <cstddef>
#include <vector>

int permCheck(std::vector<int> a)
{
    std::sort(a.begin(), a.end());

    for (std::size_t k = 0; k < a.size(); ++k) {
        if (k + 1 < a.size() && a[k] != static_cast<int>(k) + 1) {
            return 0;
        }
    }

    return 1;
}