Compilare: user.cpp: In function ‘bool slv(std::pair<int, int>)’: user.cpp:87:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( pos == col.size() - 1 ) ^ user.cpp: In function ‘int main()’: user.cpp:121:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i < plg.size(); i ++ ) { ^ user.cpp:131:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < lst2.size(); j ++ ) { ^ user.cpp:138:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < lst1.size(); i ++ ) ^ user.cpp:140:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < lst2.size(); i ++ ) { ^ user.cpp: In member function ‘char InParser::read_ch()’: user.cpp:14:38: 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); ^