Compilare: user.cpp: In function ‘void read()’: user.cpp:28: warning: ignoring return value of ‘FILE* fopen(const char*, const char*)’, declared with attribute warn_unused_result user.cpp:29: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:33: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void solve(std::vector<punct, std::allocator<punct> >, std::vector<punct, std::allocator<punct> >)’: user.cpp:69: warning: ignoring return value of ‘FILE* fopen(const char*, const char*)’, declared with attribute warn_unused_result