Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:32:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sons.size(); ++i) ^ user.cpp:33:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < sons.size(); ++j) ^ user.cpp:35:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sons.size(); ++i) { ^ user.cpp:40:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int d = 1; d < sons.size(); ++d) ^ user.cpp:41:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sons.size(); ++i) { ^ user.cpp:43:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == sons.size()) ^ user.cpp: In function ‘int main()’: user.cpp:64:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("petsoft.in", "r", stdin); ^ user.cpp:65:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("petsoft.out", "w", stdout); ^ user.cpp:68:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:71:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &father); ^