Compilare: user.cpp: In function ‘int main()’: user.cpp:68:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<G[node].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); ^