Compilare: user.cpp: In function ‘void euler(int)’: user.cpp:40:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < G[son].size(); ++ i) ^ user.cpp: In function ‘int main()’: user.cpp:67:35: 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, 1 << 23, stdin); ^