Compilare: user.cpp: In function ‘void DFS(int)’: user.cpp:17: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void sortare_topologica(int)’: user.cpp:25: warning: comparison between signed and unsigned integer expressions user.cpp: In function ‘void citire()’: user.cpp:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result user.cpp: In function ‘void afis()’: user.cpp:53: warning: comparison between signed and unsigned integer expressions user.cpp:50: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result user.cpp: In function ‘int main()’: user.cpp:79: warning: comparison between signed and unsigned integer expressions