Compilare: main.cpp: In function 'int main()': main.cpp:100:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( j = 0 ; j < sol.size() ; ++ j ) { ~~^~~~~~~~~~~~ main.cpp: In member function 'char InParser::read_ch()': main.cpp:22:38: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 4096, fin); ^