Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:51:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < query[nod].size(); ++i) ^ user.cpp:56:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < g[nod].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:102:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < sol.size(); ++i) ^ user.cpp:65:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("undo.in","r",stdin); ^ user.cpp:66:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("undo.out","w",stdout); ^ user.cpp:70:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for (scanf("%d %d", &N, &M); M ; --M) ^ user.cpp:72:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &op); ^ user.cpp:76:45: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &x, &y, &cost); ^ user.cpp:86:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); nr_query++; ^ user.cpp:92:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &number); ^