Compilare: user.cpp: In function ‘void firstDFS(int)’: user.cpp:17:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<R[node].size(); ++i) ^ user.cpp: In function ‘void secondDFS(int)’: user.cpp:27:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<G[node].size(); ++i) ^ user.cpp:31:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<G[node].size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:40:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hektor.in", "r", stdin); ^ user.cpp:41:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hektor.out", "w", stdout); ^ user.cpp:45:45: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &n, &m, &start, &stop); ^ user.cpp:48:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &cost[i]); ^ user.cpp:51:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x, &y); ^