Compilare: user.cpp: In function ‘void write()’: user.cpp:40:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < ctc[i].size(); j++) { ^ user.cpp: In function ‘void DFS(int)’: user.cpp:50:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < G[v].size(); i++) { ^ user.cpp: In function ‘void connect(int, int)’: user.cpp:63:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < GT[v].size(); i++) { ^ user.cpp: In function ‘void read()’: user.cpp:23:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.in", "r", stdin); ^ user.cpp:24:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:27:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^ user.cpp: In function ‘void write()’: user.cpp:37:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ctc.out", "w", stdout); ^