Compilare: user.cpp: In function ‘void tarjan(int)’: user.cpp:25:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < graph[v].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:81:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ctc.size() ;i++) ^ user.cpp:83:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < ctc[i].size();j++) ^ user.cpp:63:31: 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:64:34: 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); ^ user.cpp:65:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:72:23: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^