Compilare: main.cpp: In function 'long long int get_trapezoids()': main.cpp:45:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < slopes.size(); i++){ ~~^~~~~~~~~~~~~~~ main.cpp: In function 'void setIO(std::__cxx11::string, bool, bool)': main.cpp:7:50: 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:8:53: 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); ^