Compilare: user.cpp: In function ‘void Delete(Edge)’: user.cpp:87:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < S[tmp.x].size(); i++) ~~^~~~~~~~~~~~~~~~~ user.cpp:92:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < S[tmp.y].size(); i++) ~~^~~~~~~~~~~~~~~~~ user.cpp: In function ‘char nextch()’: user.cpp:11:36: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, BUF_SIZE, 1, fi); ^