Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:29:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sons.size(); ++i) ^ user.cpp:30:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < sons.size(); ++j) ^ user.cpp:32:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sons.size(); ++i) { ^ user.cpp:37:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int d = 1; d < sons.size(); ++d) ^ user.cpp:38:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sons.size(); ++i) { ^ user.cpp:40:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == sons.size()) ^ user.cpp: In function ‘int main()’: user.cpp:61:38: 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:62:40: 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:65:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:68:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &father); ^