Compilare: user.cpp: In function ‘int main()’: user.cpp:84:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<ANS.size();++j) ^ user.cpp:69:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gauss.in","r",stdin); ^ user.cpp:70:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gauss.out","w",stdout); ^