Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:17:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v[n].v.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:23:18: warning: unused variable ‘j’ [-Wunused-variable] int n, m, i, j, a, b, r = 0; ^ user.cpp:24:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dfs.in", "r", stdin); ^ user.cpp:25:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dfs.out", "w", stdout); ^ user.cpp:26:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &n, &m); ^ user.cpp:31:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &a, &b); ^