Compilare: main.cpp: In function 'int main()': main.cpp:87:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<g[u.nod].size(); i++) ~^~~~~~~~~~~~~~~~ main.cpp: In function 'char read_ch()': main.cpp:21:32: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(_in_buff, 1, 4096, fin); ^