Compilare: user.cpp: In function ‘void Solve()’: user.cpp:51:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int i = 1; i < V.size(); ++i ) ^ user.cpp:54:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int j = 0; j < R[a].size(); ++j ) ^ user.cpp: In function ‘void DFS()’: user.cpp:71:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int i = 0; i < G[x].size(); ++i ) ^ user.cpp: In function ‘void Input()’: user.cpp:27:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("srevni.in","r",stdin); ^ user.cpp:28:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("srevni.out","w",stdout); ^ user.cpp:31:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i%i",&N,&M); ^ user.cpp:35:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i",&a); ^ user.cpp:44:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i%i",&a,&b); ^