Compilare: user.cpp: In function ‘std::pair<PT, PT> closest_points(std::vector<PT>&, std::vector<PT>&, int, int)’: user.cpp:64:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i + 1 < v.size(); i++) { ^ user.cpp:65:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = i + 1; j < v.size() & j - i < 8; j++) { ^ user.cpp:65:31: warning: suggest parentheses around comparison in operand of ‘&’ [-Wparentheses] for (int j = i + 1; j < v.size() & j - i < 8; j++) { ^ user.cpp: In function ‘int main()’: user.cpp:78:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cmap.in", "r", stdin); ^ user.cpp:79:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("cmap.out", "w", stdout); ^