Compilare: user.cpp: In function ‘void read()’: user.cpp:21: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void dfs(int)’: user.cpp:40: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void build_graph()’: user.cpp:57: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void bfs(int)’: user.cpp:79: warning: comparison between signed and unsigned integer expressions