Compilare: main.cpp: In function 'void Union(int, int)': main.cpp:81:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < v[pozmrg[b]].size(); ++j) ~~^~~~~~~~~~~~~~~~~~~~~ main.cpp:96:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < v[pozmrg[a]].size(); ++j) ~~^~~~~~~~~~~~~~~~~~~~~ main.cpp: In member function 'char InParser::read_ch()': main.cpp:13:29: 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); ^