Compilare: main.cpp: In function 'bool check(int, int)': main.cpp:23:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int k = 0; k < s[i].size(); k++){ ~~^~~~~~~~~~~~~ main.cpp:25:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(nxt[at][c] == s[j].size()) return false; ~~~~~~~~~~~^~~~~~~~~~~~~~ main.cpp: In function 'void setIO(std::__cxx11::string, bool, bool)': main.cpp:11:50: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] if(input) freopen(inputname.c_str(), "r", stdin); ^ main.cpp:12:53: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] if(output) freopen(outputname.c_str(), "w", stdout); ^