Compilare: user.cpp: In function ‘bool notOkay(int)’: user.cpp:82:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(act.size() > K) { ^ user.cpp: In function ‘bool Okay(int)’: user.cpp:115:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(act.size() > K) ^ user.cpp: In function ‘int main()’: user.cpp:192:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < sol.size() ; ++ i) ^ user.cpp:194:45: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1 ; i <= N && sol.size() != K ; ++ i) ^ user.cpp:169:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(infile, "r", stdin); ^ user.cpp:170:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(outfile, "w", stdout); ^