Compilare: main.cpp: In function 'bool solve(std::vector<std::vector<long double> >&, std::vector<long double>&, std::vector<long double>&)': main.cpp:39:18: warning: suggest parentheses around '&&' within '||' [-Wparentheses] while(at < m and (fabs(a[i][at]) < 1e-10) or vis[at]) at++; ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp: In function 'void setIO(std::__cxx11::string, bool, bool)': main.cpp:7:51: 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:8:54: 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); ^