Compilare: main.cpp: In function 'int main()': main.cpp:94:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < edges[0].size(); i++) { ~~^~~~~~~~~~~~~~~~~ main.cpp:97:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < edges[1].size(); i++) { ~~^~~~~~~~~~~~~~~~~ main.cpp:105:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < needed.size(); i++) unionSet(needed[i].pA, needed[i].pB); ~~^~~~~~~~~~~~~~~ main.cpp:108:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; needed.size() < k && i < optional.size(); i++) { ~~~~~~~~~~~~~~^~~ main.cpp:108:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; needed.size() < k && i < optional.size(); i++) { ~~^~~~~~~~~~~~~~~~~ main.cpp:115:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < edges[0].size(); i++) { ~~^~~~~~~~~~~~~~~~~ main.cpp:121:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < needed.size(); i++) { ~~^~~~~~~~~~~~~~~ main.cpp: In function 'void setupIO(const string&)': main.cpp:54:56: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen((PROB + ".in").c_str(), "r", stdin); ^ main.cpp:55:58: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen((PROB + ".out").c_str(), "w", stdout); ^