Compilare: main.cpp: In function 'std::pair<long unsigned int, long unsigned int> closest_pair(const std::vector<std::pair<long int, long int> >&, std::size_t, std::size_t, std::vector<std::pair<long unsigned int, long int> >&)': main.cpp:61:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(std::size_t itr = 0; itr < i; ++itr) ~~~~^~~ main.cpp:63:55: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(std::size_t jtr = itr + 1; jtr < itr + 8 && jtr < i; ++jtr) ~~~~^~~ main.cpp: In function 'int main(int, char**)': main.cpp:88:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(std::size_t itr = 0; itr < n; ++itr) ~~~~^~~ main.cpp:105:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(std::size_t itr = 0; itr < n; ++itr) ~~~~^~~