Compilare: user.cpp: In function ‘void gen_inv(int)’: user.cpp:17: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void dfs_visit(int, std::vector<std::vector<int, std::allocator<int> >, std::allocator<std::vector<int, std::allocator<int> > > >&, int)’: user.cpp:30: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘int main()’: user.cpp:88: warning: comparison between signed and unsigned integer expressions user.cpp:70: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:75: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result